I have had bi-amped Maggie 1.6's with an active Bryston 10B crossover (analog) for 10 or so years. In my modest system the difference was quite astounding. As someone has pointed out, cleaner, more dynamic, and musical vs. passive crossovers.
A caveat though. As richopp pointed out, Maggie crossovers were designed to be bi-amped if so desired and gutting the passives and rewiring was pretty straight forward. I did add new binding posts and plates when doing the conversion but could have used the stock pieces. Maggies are also known for not having the highest quality components in their passive crossovers (see the countless threads on the Planar Asylum of crossover component upgrades). Also, the Bryston 10B has settings that mimic the stock crossover frequencies and slopes, although I ended up preferring different settings.
Point is - it made a tremendous difference in my setup. Well worth the money (extra 2 channel amp and interconnects) and effort.
Not as intimidating to do as you might expect (geez, even I was able to do the conversion).
As to passive crossover component upgrades or digital vs. analog active I have no experience and can't comment.
The Elliot Sound Products white paper posted earlier on active vs. passive is excellent. Good luck with your quest.
Jim S.
