I imagine if you went the whole hog, picked up a good electronic crossover, and fed different signals into the two amps there would be more difference -- not saying that's worth DOING, just agreeing that "simple bi-amping" (both amplifiers get the same signal) probably isn't worth the effort.

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8