DX10 was never about performance gains. It's about removing limitations of DX9 such as individual texture size and unifying the shaders. I don't get they hype with DX10, it was misdirected. The hype belongs to the hardware that can use DX10 just because we've crossed a perfomance landmark. Looking at a card like
7950 GX2, here's a dual GPU card much like the upcoming GTX 295. Essentially two cards in one. People critisized the card because it didn't perform as well people thought it should based on the hardware. One of the reasons is due to a limitation in DX9. GTX 295 should do better in DX10 over DX9.
Although it's hard to compare because to take advantage DX10 capable hardware you have to design the game only with DX10. That's the only way you can completely eliminate the limitations from DX9. At the same time they to have design the game exclusively for high end hardware. We'll have a better idea of what DX10 is about with the next gen of consoles for this reason.
If you look at videocards before 8800GTX there is a huge gap. DX10 was rushed though. Hardware developers didn't have time to write proper drivers and MS had to cancel many of the more interesting features. They should have waited until what we call DX11 was ready and just release everything as DX10.
Eventually DX10 will be mandatory for the best games. This does not mean DX9 will disappear completely. Even today still have new games that can run on DX8. If you run games in DX8 mode you have to turn down the settings even with the same hardware. Your frames per second will go up but you will have shittier textures and lose avanced lighting along with other features.
DX10 hardware should be able to support many of the essential DX11 features, since it is based on DX10. It seems like they are focussing GPGPU features such as encoding with DX11. So it's not that important in terms DX10 hardware's ability to run future games.
Don't worry about DX11. If you wait until Q2, those cars will be impressive with or without DX11. If you don't want to wait that long, the GTX 285 will be excellent too.
<message edited by Agent Ghost on Dec 16, 2008 23:39>