I biamp in one of my systems. I use a pair of mono amps to handle the bass and a different pair of mono amps to handle the mids and highs. The mid/high have the bass rolled off using high quality caps at the amp inputs and there is an adjustable unit to balance the bass (which goes through untouched) with the mids/highs.
This is the system that Richard Vandersteen uses and it works very well with my big Vandersteens, although many would prefer to avoid the complexity of four mono amps with an external adjustable crossover for the bass.
Does it sound better done this way? I was pleased to find that it does and the improvement warranted the extra system complexity.
Whether you would get the same gains depends entirely on your particular system.