I was wondering if the same people arguing against the 10mm difference in bb width make the same arguments against 165mm vs 175mm cranks. Everyone claims that the shorter cranks are way better with fewer pedal strikes, but that's the same difference we're talking about here. People argue the same with handlebar widths as well.
2010 Demo 8
Apples and oranges. Your demo 9 is not even in the same league s the new demo 8.
Demo 9, Demo 8 and Demo 7 ride VERY differently - with the 8 and 7 being somewhat closer to each other than the 9, which is a completely different beast, especially in terms of suspension performance at higher speeds which is very noticeable on square edge bumps, and overall frame bulk (the Demo 9 was a beast like the Banshee Scream)
the Demo 7 with the travel chip removed from the shock gives 7.9" of rear bounce, and if pared with a Fox 40 or Boxxer and a sensible build, is a very capable DH racing machine
alot of people hate on MBA magazine (USA) but they've been testing and riding bikes for many years, including all the top USA exotica and said the Demo 7 with the setup mentioned above was the most capable DH rig they'd ever tested
of course the "new" 2010 Demo 8 is taking it a step even further in terms of geometry and suspension refinements
Mythic / Da Kine / Esher Shore / Freeborn
No experience here with 83mm BBs, but when I change from my HT2 XT or XTR cranks to my Campy road bike cranks, it sure does feel different. Same when I moved from normal cranks to outboard bearings (HT2) the first time. Dunno the Q-factor of both, but I'm pretty sure we are more sensitive to small changes in our equipment then we might think.
How's your Uzzi VP so far?
I don't think the Q factor changed from ISIS to X-type cranksets.