I used the Delta Pro 12.....maybe a bit heavy but I'm not using them every week. For the HF section; one cabinet has a straight piezo array that I build myself, the other a melded one that I bought from SpeakerHardware. The straight was easy enough to make, the melded looked like it was better left to someone who had the right jigs. The melded definitely offers a benefit, but both are pretty good. I know it seems an odd combination to have one of each.....ultimately I'd like 4 OT12; two straight and two melded.
One thing I did, that's not in the plans, was put a curve on the front of my OT12 cabinets. It is an idea I copied from someone's build thread.....in my opinion it does look nicer, but the truth is they don't pack as nicely.