Any chance of some samples of what you mean?
I've got a 7D and have seen no problems with anything thus far (but then that's all relative as to how your last camera performed).
Have you tried RAW-converting in DPP? Just for a test, set it to 'standard' picture style, sharpness 3, noise reduction 1/0, i've never had a problem with mine for that on iso100, and i've shot birds at 800/1600iso (to get shutter up over 1/500s) with acceptable quality after a bit of DPP's NR.