My ODB-3 has been doing me right.
I can run it real light for either a nice tube-ish warmth (highs-control and drive turned all the way down); I can sort of simulate a distorted rhythm guitar+bass by running the treble and drive at about 12:00, and the blend back at about 8:30 or 9:00... Here's one: really decent dub-tone with the settings highs=7:00, lows=4:00, blend=4:00, drive=7:00, and back-off the bass' neck pickup volume as-necessary (tone on the bass all the way down, of course).
I always run a compressor before the ODB, but these sounds aren't too bad without. Especially for the dub tone example; if you back-off the outupt of the bass just right, it acts like light compression on it's own - it's a good sound that I can't get with any other combination of bass/amp/compressor settings.
On the other hand (!), if I could only choose between compression or distortion, I'd definately choose COMPRESSION. I use mine full-time, and it does fill-out the sound, just as your guitarist says. I wouldn't want to be without compression, but the combination is powerful! Run compressor first, then OD.
Joe