I purchased A7 just before A8 came out so I got a free upgrade. I converted my simple ODE physics game to PhysX and distributed it to some testers. I believe 2/5 couldn't get the game to start. 2/5 had completely messed up physics where their player was "bucking" instead of driving. 1/5 who had an Nvidia card and was programming PhysX into his own game on a different engine, couldn't run it out of the box, and when he fixed it, it still had the bucking problem if I recall.

I haven't really tried to figure out why this all happened but if 5 people I test with can not play it easily, I give up. ODE physics is currently working fine for them.