I usually wait until the new stable is ready and then upgrade. If everything seems to be OK, I then dist-upgrade, check again. I've never had any problems. As most of my systems are remote servers I have an anxious minute or two if an upgrade also requires a kernel update (and thus a reboot).
I once had a upgrade go wrong on my laptop, but that was due to me installing some packages from Debian Multimedia that had dependency problems in the testing version I was moving to.