As said before, I run sometimes in quad, but can't handle drastic effects neither (in most cases). The goal is having a sense of depth: you don't have to drive your stereo effects hard to do that. On the other side, if you want a total psychedelic setup, it's an other thing.
When you run in multiple amps/cabs having "switching" effects, the "additional effective" power is not the same as driving two (or four) amps in "straight" mode. So, perhaps you're better with not too distinct, but more blended, and/or overlapping effects. This way you can have two (or more) less powerfull amps playing simultaneously but with less effects, and getting that depth with some power at the same time (saving you some extra weight).
If you want it complete psychedelic sound you'll need old school attitude,
But with modern techniques: http://www.physicalfitnet.com/workouts_video_browse_by/all.aspx
Heavy amps, but you will not want to be heavy on psychedelic clothes (well forget the furrs and bring the OTs).
As to say that it is useless in live settings, well a big room is not the same thing a small one, and as outdoor neither (of course). And orientation of the cabs count also... no (?)
And driving two amps into "distortion" with a slight delay helps also in "some" cases, like many have mentioned before. OKAY, you can do that in one amp, but a "slight stereo" might help in my opinion.