Jas, according to Ubisoft, DX 10.1 increases performance whether or not the implementation gets screwed up.
At least that is how I understand the interview.

Which makes it especially weird that Ubisoft later on says they know for sure the performance improvements seen on ATI hardware are due to bugs.

So 10.1 does improve performance, unless on ati hardware, in which case performance improvements are only caused by ty implementation?
Hmmmk