I have been running woody with no stability complaints for quite a while; I am running woody with those packages from sid that I have a good reason to install, such as KDE 2.2.1 (i.e., the sid version has fixed some glitch, offers a new feature, etc.). Going from potato to woody should be painless (aside from the volume of downloads - what a difference a dsl connection makes :)). However, I have heard that there may be some glitches if you are going from Progeny to woody. I have not tried it recently (i.e., following their recent upgrade instructions, which hopefully catch any big pitfalls), but I have heard of problems in doing it without guidance. A straight apt-get dist-upgrade from progeny to woody may result in some unexpected failures (i.e. I know of someone doing a straight Progeny install, then adjusting the /etc/apt/sources.list to woody, and doing an apt-get dist-upgrade, and ending up killing their network connection).
For a workstation installation, going to woody is worth the trouble. Bruce