I have the 7D and use it for all my astro work. Noise isn't as good as the 5D but you can still take very good astro photo's with it. I enjoy using the camera a lot.
I used to have lots of examples on my website, with shot details, but since changing my website provider haven't really re-built that. You can still find several there taken with the 7D like all the recent astro shots like this:
http://rogergroom.com/astro-photogra...iridium-flare/
Seeing your other thread I thought you'd have gone with the 60d?
Regards,
Roger.