One down, one or two to go
Until DX11 does not become mainstream (eg. 90% of the users will have DX11 capable cards) you can't expect to see differences between DX11 and DX9/10 modes. Why? Because they won't make games where one player sees something and the other does not, to the point that will actually mean something and affect the gameplay.
So anyone that bought the cards for DX11 will not get anything extra from the DX11 code path. No developer that wants to sell a game would code it so that you'd need a new card to play the game. They would not shoot themselves in the foot.
DX11 is now in the position PhysX was, and I'm not necessarily speaking about the CUDA PhysX version, but the original PhysX by Ageia, when you needed a PCI card for it. It had and still has great potential, but you can't use it to it's full extent until people embrace it and make it mainstream. Until then, all the developers can do is to use certain features here and there, so that it gives you a glimpse of what it could be, but not so much that it makes a difference and modifies the experience too much. They just don't want to give up customers, it's not just that they don't want to use the technology.
And when DX11 finally becomes mainstream, in 6-12-18 months, the current DX11 cards will be nearly obsolete performance wise... truly tragic. But that's the way the cookie crumbles...
It's a bit of a troll-ish post (it may seem that way, if you have an ATI DX11 card), and I will get "-1" all round but it's the truth if you think about it from a safe distance. Too bad you... yes... you... the one clicking the "Useless message" icon, won't even get to this last paragraph.