bi-amping, in my experience, is best with 4 identical channels of amplification and a speaker allowing separate low octave and upper octave inputs. the reason is my priority is always coherency first and foremost. and if the amps for upper and lower octaves are different, unless the speaker is designed with those particular amps in mind, you will always fight for optimal coherency. and in theory that should more control the speaker compared to just two of those same channels, resulting is better performance; the amps are less stressed, the speaker more under control, with a better soundstage, more authority in the lower octaves, and lower noise.
that said, it’s hard to generalize about bi-amping, each case is separate. too many variables. and if you have the budget for 4 channels of amplification, most times investing in better 2 channels of amplification and not bi-amping will equal a higher level of musical result. based on my personal priorites.
OTOH if ultimate dynamics or bass punch is more significant than coherency, then all bets are off and bi amp to your heart’s content. for me though, i’d rather have the very finest first watt and listen happily ever after which would be the better performing 2 channels.
so quality almost always trumps quantity.
one case is tempting, where you have a low wattage SET tube amp, and need something to kick it on the bass, so you find a solid state amp for the bass. maybe your best overall result is with those different amps, but you will always be fighting your bass being solid state and not ’of a piece’ with the SET tubed upper octave amplification. but you might love it anyway. comes down to what you like. no rules.
at the modest level of gear, maybe you have a multi-channel amp you want to use to bi-amp some speakers. in that case, it does make sense to do it. again, hard to generalize.