I tried to do apples to apples comparison. Dx10 in win7 x64 is faster and scores a higher score, but only due to peak fps. Avg fps is still slower and there is much more micro stutter in win7. Not to mention min fps in win7 is 6 fps for dx10 and dx 11.
there is some problems right now particularly on the ATI/AMD side with this demanding Unigine demo. From the Radeon HD 5000 "Evergreen" graphics cards that we have tested, all that is displayed using the Catalyst 10.4 drivers found in Ubuntu 10.04 are psychedelic colors.
So I filled a bug report about this and they say they are going to fix it "as soon as possible". We'll have to wait and see. But I'm quite surprised by this prompt response. I wonder if the fact that the bug was being spelled out in this Phoronix article has anything to do with it .