I'm hoping the 7d will key better than my HDV camera, which isn't so great. Will the high data rate theoretically improve the chances of getting a good key? Who has keyed so far?

Check this:
The Great Chroma Key Smackdown - Canon 7D on Vimeo

I have only done one quick interview in our studio with the 7D... and as rush a job as it was one thing was really clear. They 7D footage was WAY easier to key than HDV! I think it has the same chroma sampling as HDV, but there is just so much more information there and less noise which must help quite a bit. So I guess that's good news... oh, and I just used keylight in aftereffects. I hear you can get even better results with some of the other plugins such as dvmatte pro.

I have used a chroma key setup with Reflectmedia and it seems to be the same as my A1. I didn't notice anything different.

I have used a chroma key setup with Reflectmedia and it seems to be the same as my A1. I didn't notice anything different.

Well that's disappointing to hear...