Amp is all but the "same". Bimmertech changes something on the board to call it "special". All the plugs and harnesses are the same - I'm using their wiring harness on my A-F amp in the X3 (per Nelson - even though A-F manual says not to use factory harness for power. Hmmm....)
All of the BMWs with the 676 amp/speaker package us the same plug (I'd bet even the HK system uses the same plug). Most people probably see the value in the center (having one in a a home theater makes a difference) and with the ability to play DVD's - it's pretty much needed for "surround sound" (again - marketing the Logic 7 system)
I'm using the audioson software - each manufacturer puts their own spin on it - I should have pulled up the A-F software to see if it would connect to my Audioson - something for another day.
http://www.jehnert.de/shop/doorboard...woofer-system/
Just the mids-tweets - bought them used without woofers for a steal ...