Hi, I owned 30D and upgraded to 7D in spring. I'm very satisfied, in term of noise 7D is one f-stop better, iso3200 is quite acceptable for me.
I feel 7D is noisy at every iso level, but it's possible to use software for noise reduction, try it!
7D is superb camera, noise is not everything. With 30D I had issue with AF in low light, also AF precision was not good. Finally I found out microadjustment very imporving my lenses.
Before with 30D: iso max 800, aperture almost f/4 to get proper focus.
After with 7D: iso max 1600, but I can use f/2.2 with my primes because I have better AF including MA.
I'm very satistied with 7D + 28/1.8 + 85/1.8.