I own a POD XT live, I've never used it live, only in practice room, but gotta tell you It's fun... tons of effects, lots of parameters to tweak and as the matter of fact it is really easy to use (a couple of flips on the manual and you are ready to go, the thing is, if you have ears, you can use it).
Regarding the use of pedals, I've seen the best results comes of using both worlds, pedals and modeled effects, just saw this Metal band (guys who studied in a schooll that has conection to bearkley music schooll in Mexico), both guitar players had the same rig a zoom unit (dunno wich), conected to a boss GT6 conected to a metal zone pedal. Gotta say, tight sound like it a lot.
Besides tweaking with the computer is so much easier than tweaking on the pedalboard. Now if you are into experimental stuff, I've read about this software called "Trash", it seems to be you thing, it's all about distortion, but not like regular metal distortion a la Slayer, we are talking blown speakers, fried capacitors, experimental stuff, you may wanna check it.
Power corrupts. Absolute power is kinda neat.