Well the 7D is a lovely camera to use. Sure, it's "only" 18MP, i.e. no more than the 60D or the 600D, but using it feels like luxury.
It feels VERY snappy and responsive. You press that button and your pic gets taken right then, provided you had focus confirmed with your half-press beforehand. It can do up to 8FPS, so even in single-shot mode, it will be ready for the next shot before you are ready to press the shutter button again. And you can keep on and on pressing as fast as you like and it'll keep up.
Its build quality is excellent. Once you've used a 7D, I don't think you'll want to go back to the x00D (e.g. 600D etc.) models. (Admittedly, I have never used a 60D, so I can't comment on that, but the 60D lacks AF microadjust, which seems to me a really bad thing, and I suspect that it would be a very bad thing for you, given that you have the 50/1.2 lens, which obviously will have a VERY thin depth of field wide-open.)
I really suggest that, having that 50/1.2 lens, you should be looking at a camera to do it justice, i.e. the 7D.
You will not regret it. (Your wallet might, but if you have the 50/1.2, it suggests that you're not on too tight a budget.)
Oh, and the DIGIC4 vs. DIGIC2 thing? The more powerful processor is what drives the camera to be so fast and responsive, and give you your up-to-8FPS maximum shooting rate. It also speeds up the in-camera noise reduction that gets applied to images if you're shooting at high ISO or with long exposures. The 7D has TWO DIGIC4 processors to really give it some throughput.
Hope this helps,