I've never owned a IIC+ to compare but the Lead 2 Yellow is easily the best lead tone ever in the universe (not to use a generalization or anything :lol: )
PLUS it has seven other modes. Coupled with the 2:90 you've got the different mode switches there to for even more options.
There's no comparing the TriAxis to an amp head - the TriAxis wins every time. :mrgreen:
If you read my review (see the other message thread), you'll find that tone suitably matched in a Triaxis/2:Ninety rig, but where it differs that the Triaxis rig is a full stereo setup, so in that regard, it could differ slightly to your ears. But live or on a recording, people will hear your Triaxis rig and think "Mark IIc+" or "Mark IV" without blinking an eye.
Nothing personal -- not picking a fight (I swear), but you have the 2:Fifty and the 20/20, so what you're used to hearing is significantly different sounding than the Triaxis through a 2:Ninety. Neither of your amps have the simul-class power block from the Mark series, so while your Triaxis rig sounds great, it's not the full-on Mark-series tone that you get from the 2:Ninety (and I've owned the 2:Fifty, too). It really is noticeably different.
Scottkahn; you're exactly correct. The set-up using the 50/50 and the 20/20 sounds nothing like the 2:90, it is the one I currently use for live situations. But after being in music for over 30 yrs, 20 of which have been in the industry, and having countless rigs laying around at my disposal I'm quite sure I know how the 2 set-ups differ... in both live and studio.