I play a Power Screamer through my Fender Deluxe Reverb, and it's really nice. Gets that nice bluesy break-up tone, and it can get quite dirty when you need it to. The boost function is really useful too.
Having said all that, I would probably have tried out a Tonebone pedal before buying the Power Screamer. With the employed tube, it will clean up with the volume knob like a cranked amp will do.