I was interrupted while composing this post so forgive some redundancy, but I will include transient peaks in the discussion as I think they are relevant.
I have ignored other debated aspects of passive biamping such as the controversial theory about woofer EMF effect on tweeter. Biamping is a pretty complex topic and I think detailed discussion would be best taken up on a more appropriate thread. IME it's far too easy for posters to get caught up in generalizations and absolutes when in fact there are many variables involved, and the many permutations of what's loosely referred to as biamping.
Bonzer post there SoM!
I still remain in the camp which says that passive biamping is a waste of wire, amps and time. Whatever theoretical benefits come before the passive crossover, they are nullified as soon as they meet the latter. Heck, I even have a spare 2ch Emotiva amp here (and loads of wire) and my 5509 allows for 'biamping' so I could even do it at no cost if I wanted to it. So it's only the time that would be wasted. And still I choose not to bother... ;)
EDIT: Actually that was with my last speakers. My current speakers, being designed for professional, not audiophile, use don't have the necessary terminals. I was forgetting that part! LOL.