CM7 on our Captivates is not a perfect solution yet. It is pretty stable, very few OS issues. My issues with it are the battery life, and poor camera options. I find our camera to be superior as a point and shoot, and use it a lot. When I had CM 7, I stopped taking pics. The camera app is where you start getting FCs and the camera replacement apps suck as well, when compared to the stock Samsung camera.
I currently get less than half the battery life from it as well, though I did narrow to where some extra drain was coming from. The problem was still with CM7 not yet handling power management too well yet, which is understandable in a pre-beta release where they have yet to even look at it.
It is great for pre-beta status, which is what the devs still call it. It may not be for everyone yet. I have high hopes however, with the i9000 release. There is a long history and current capability through a re-oriented kernel, for Captivates to run i9000 just fine. Most of the custom ROMs are doing that now in fact.
Probably only days before there are ROMs for us running this. The other big win, if we are lucky, is if Samsung releases their source and drivers in such a way that would assist the CM7 guys in some of their remaining issues (mostly closed source drivers).
But I am excited enough over running a Samsung Gingerbread ROM.