I use sprutcam 8 and I have great luck with it. I have the occasional crash, but not very often, usually only if I click around while it's calculating toolpaths.
I've done some pretty in-depth toolpath stuff with it as well. I don't think you can go wrong with v8. I'm really glad I never had to mess around with 7. I probably wouldn't have chucked it thru the window if I had that many problems with it.
Wade