So, I've thrown the digitech rp500 into the mix and spent a lot more time with the TC.
The digitech really isn't what I'm looking for, which is too bad because it's really well made. You could probably use it to smash all the other units to pieces and turn around and play your set. The delays and reverbs sound good, but I couldn't push things into the sort of wall of sound territory I'm going for. The distortions and amp models on the other hand are, to me, very very bad. I think it's sounds like these that make us regard these types of units as bull shit. On the usability scale, it falls in between the TC and Boss.
I'm not ready to declare it the winner but, I've changed my tune regarding the TC. It takes a lot more work than the other units, but it has a kind of pragmatic style that I can relate to. In that sense, I like that there's no modeling, it's its own thing. The analog distortion really does sound significantly better than the other units. It's pretty basic distortion sound, but the fact that it's not trying to be all tones for all songs is probably what makes it so usable. Unlike the other units it doesn't have a built in expression pedal, fortunately I had one to hook up. You can set it up to do a lot of cool things, some of which the boss can do others it can't. In particular I liked setting it to control the drive level of the distortion, I was easily able to control some really cool feedback swells. On the down side It doesn't have a wha setting, maybe you can set up the expression pedal to sweep the eq but I didn't get there. It might be for the best anyhow, I should probably just make a nice real wha. The other effects sound really good and if anything they suffer from too many editable parameters. Unless you really love a certain chorus or phaser or whatever I think the modulation fx would probably get you where you need to go. For my purposes it would be more than enough.
I had band practice tonight and planned on running our set with each unit to see how they sounded in context, but I only got to A/B-ing my regular pedals with the TC. I kept futzing with the delay but really couldn't get it to sound as good as my BYOC delay pedal. I got it close though, and there's a lot of functionality that the TC (and any other multi effect) has that is truly useful. There were some songs that I preferred the TC drive to my rat clone, and having a distortion channel as well as a boost is really useful. The TC doesn't have as many bells and whistles the others and it's a steeper learning curve but it doesn't feel as phony as the other units. If I stick with the TC I'd likely keep my delay on my pedal board, the rat might be redundant but a real wha and a big thick fuzz would be "necessary" as well.
I look forward to trying the boss with the band, and after I return the digitech I'll order the line 6.