How many of you have tried the current demos that are coming out for the DirectX 10 games?

I know there has been a lot of talk about DirectX 10 and DirectX10.1 lately. Some say cards designed on the DirectX 10 will not run the DirectX 10.1, while others say the opposite. The video card manufactures say that it's going to be no different than the way they handled DirectX 9 and its updates. It definitely would suck if they did make it so the DirectX 10 cards woudln't support the DirectX 10.1. I think it would eventually bite them in the ass though. To many people have already boughten DirectX 10 compatible cards that would be left in the dust.

After recently getting my Vista install to finally run my SLI setup, I have downloaded a few of the newer game benchmarks that utilize DirectX 10.. Man do they look friggen sweet. I am curious to see how well the lower to mid range cards handle them though.