It was pretty bad last time I tried to run NetBSD on my vaxen. Back around NetBSD 1.5.2 or something like that I was able to install via mopboot on my MicroVax 3600 and a few VaxStation 3100's. Years later I tried to boot it up again and it couldn't boot without crashing. I tried a later release and it wasn't much better. Install went OK, but the userland code was compiled with some funky options that caused it to throw invalid instruction exceptions. By then I had my VMS hobbyist kit.
-Dave