BillFitzmaurice.info

There isn't anything more ideal for the situation you described than a device I already have used in that scenario....a keyboard amp/mini P.A.! Mine even has built in effects and correct connectivity to be easily expandable. Oh and did I mention it is stout enough to support Guitar, Vocals and my bass at the same time in coffee shops! Sound quality is great throughout the range of keyboards so that covers all the instruments! If you need more mics it is easier to add a small mixer to one of these than if you work it the other way around!
Larger coffee shop? Add a sub as most of them come with aux outs and sub outs! I think I might make a simplex sub with a plate amp to augment mine, but I haven't needed it yet!

Nothing trumps experience except more experience!

That's a cool idea. I wish I'd thought of that Since my original posting, I've actually decided to take a somewhat different approach after considering what other people are using for these low volume gigs and realizing that the Jack 10s I built aren't really all that "imposing" when compared to, say, 12" 2-ways. So, I've decided to go with the Jacks for now and have picked up a Peavey PV14 mixer and a Behringer NU1000DSP to get the ball rolling. The PV14 looks to be quite capable for the money and it should be able to cover everything I need for small gigs and beyond. I chose the Behringer because of its largely decent reviews, low price point and DSP functionality with the intention of upgrading to a higher quality amp once I'm making enough money to justify the expense. My plan is to construct a rack case to hold the mixer and amp and then strap everything onto my dolly for a single trip in and out.

The SLA Pros and sub are definitely still on my radar because they're a much more elegant way to meet my needs, but I'll have to table them for now after spending money on the other gear I needed to make this happen.