Thanks for everyone's replies. They are all very much appreciated.
I have spent the last week (possibly more) investigating this purchase. For me, this is a big purchase

I see that a couple of you have mentioned making several zero clearance sleds for all the various angles. Although I like the sled, and it finally made me understand how to actually use a circular saw (thx Bill!), I have several issues with them:
Firstly is that I keep nicking the edge when I take the saw off the sled after a cut. I KNOW I should just wait for the blade to stop spinning, but I am so eager to see if I got the cut right, this has never worked. My action on removing the saw is now much better, so this rarely happens, but it still does from time to time. Because I nicked the edge of my old sled so many times, I recut it to a 3° sled for the DRs and this worked well. Maybe I should just keep recutting the sleds with bigger angles as I damage them - like a conveyor belt of sleds.
The second reason is that I get pissed off with screwing and unscrewing the sled to the workpiece every time I do a cut. I should have made the base of my sled wider so that I could use clamps, but hindsight is a wonderful thing. I am worried that even with clamps on the left hand side of the sled (based on where I am standing during a cut), the sled at the cutline would rise up as the clamp point is 6"+ away from the cutline. I already find that if I use my screwholes toward the left of the sled, I can get a bit of lift on the cutline - moving the anchor point further leftwards can only increase this problem.
Finally, that's quite a bit of wood if I have to create a sled for all the angles. In the DR, there a total of 8 different angles (sorry, 9 with the 90° cut). I am also planning to build some more T30s, so that would add to that total (although there are probably some angles that are the same). The wood to make all of this would probably cost as much as a tracksaw

I also have an issue with space - I'm a messy builder, and all those sleds would end up all over the garage... I'd be ages finding the one I needed!!
So as you might be able to tell, the tracksaw purchase has already been justified in my own head. Currently I have no wife (or husband

) to persuade in order to make the purchase with the 'family budget', so I'd better buy one whilst I can!!
I have been finding it hard to justify a Festool/Dewalt/Makita - I had decided that Makita & DeWalt were not in the running... if I'm going up toward £300, then I'd just bite the bullet and pay the £325 for the Festy - this price tag is high though, for someone who isn't an out-and-out woodworker. I just want something to make building cabs (and occasionally other things) quicker, easier and more of a pleasure. It's not like I can't build a cab right now with the kit I have, so £325 gains me nothing other than cleaner, more accurate cuts (which get covered in duratex anyway) and a nicer building experience. It's hard for me to justify any of the 'brandname' saws.
I have therefore been looking at the Scheppach again, as I discovered that it DOES cut on the line for straight and bevel cuts

ScrewFix sells the PL45 and 800mm of guide rail for £130 - a pretty good deal except for the 145mm sawblade that is only available from Scheppach

and that tiny track. Moving on to the CS55/PL55, I have read every review on the internet (including German and French!) and I think it's a good saw. It has it's flaws, but most are quite easily fixed. Some people on the review sites say something like "if I'm going to buy a saw, it should just work out of the box with out any adjustment". This doesn't bother me if I have to spend an hour getting the saw nicely set up to save quite a bit of money - if I spend an hour to save £150, that probably the best (paid) hour's work I have ever done. I don't think that any of them have noticed that even the Festool needs to be adjusted (to the rail) and set-up (splinter guard cut)!! Luckily all of the set-up adjustments to the saw are reversible, so that if it does go bang, you'll still be ok with the guarantee. To me, the biggest problem I have seen with the Scheppach is the track. It's not compatible with any others, so you are reliant on Scheppach if you ever want to buy any more in the future. There have also been quite a few reports of bent rails. Whether this is a manufacturing fault or a transportation fault hasn't been fully established, but that rail needs to be flat - anything else is (s)crap.
I had also seen a saw on a German site. A Batavia T-Raxx:


£99 delivered, and it fits the Makita and Festool tracks. I had initally looked at this saw and rejected it as I couldn't find any reviews of it - I would have been investing in a big unknown. I have since discovered that it is almost the same as the Makita:

People have been suggesting that some enterprising Chinese guy nicked the moulds for the Makita and then started churning out T-Raxx saws. It's far more likely however, that the Makita saw is an OEM saw... a Chinese manufacturer designed it and then sold it to Makita (with a bit of input from them on what features they wanted on it). This happens all the time - think of the 'Super OEM' turntables: Stanton ST.150, Reloop RP7000 (& 8000 with midi on it), Sync XTRM1, Akiyama Acura, American DJ HTD4.5 - there are all built by the same manufacturer in China and each brand who has purchased them have made small tweaks to the design, but underneath it's the same deck. For a more striking example:
American Audio Versadeck
DJinn Pro:
Citronic MP-X10 (with removable rack ears)

& there are about 5 other 'manufacturers' of this unit that I know of (as I've got the MP-X10 myself - used for in-van mixing on the way to parties!

)
So I am assuming that the saw has been made for Makita by an OEM (although I cannot confirm this, it really looks this way). This OEM has also made the Batavia T-raxx and I have then found the Triton Track Saw that also seems to have come from the same mould:
It's a definite pattern and I'm 95% sure I'm on the money with this one! I found a second Batavia model, 1400W with a Alu storage case, anti-tilt, a kickback stop and the electronics of the Makita (soft start, speed adjust dial and constant speed adjustment when cutting):
(Compare this to the other Batavia model above and note the extra knobs on the base for the anti-tilt, kickback prevention and parallel guide, as well as a speed adjust dial to the right of the motor)
Best of all, I found it on Amazon UK, so no messing around with European distributors if anything goes wrong. I understand that some components may be lower quality, but I doubt it that it will be much lower than the Makita - you'd be paying at least £50 for the colour and the name badge! Comparing the Batavia to the Makita, I've noticed that it doesn't have a 22.5° stop nor does it go to -1°. I am also under the impression that it doesn't have a 45° stop, as it doesn't have a knob where the Makita does, but the manual mentions a 45° stop on page 34, so I am unsure on this one. It would be nice to have the 45° positive stop, but if it doesn't, I'm not going to lose sleep over it. Neither saw has a riving knife either, although as they both have anti-kickback, I am thinking that this makes up for it a bit.
Finally, the clincher for me was finding the Batavia site (took a while, mind you!) and finding the manual.
http://www.batavia.eu/products/13-t-rax ... manual.pdf. It's good and looks like some time has been spent on it and it's not just some Chinese thrown into Google translate! It's things like this that I often find can give away the quality of an item. If the manual has been thrown together by the 'manufacturer', how do you think the tool was made??
So it's looking like £179 for the thing from Amazon, combined with £40 for a 1.4m (55") section of Makita track - this is actually cheaper than the T-Raxx variant (which is actually 2 rails of 800mm each). I'll probably get the T-Raxx track later on, so that I have a small rail for the smaller cuts. Join all 3 bits up, and I will have 3m of track - plenty to chop an 8x4 to size. I deemed buying the 3m Makita track a bit of a waste, as it would only get used when chopping up a full sheet - something I don't do very often. At £130 it's also v. expensive when compared to the 1.4m track.
Sorry for the long post. I thought I'd explain my reasoning. There's a week of research gone into this, so I thought I'd share my findings. Feel free to comment

Thanks.