I had a Keeley 4 knob compressor for a while and it did manage to make my rig at the time (SS head, ported 410) sound a bit better, but I found it killed the dynamics I was so used to controlling with my fingerstyle. And then it started acting funny - low volume, couldn't alter the compression level, etc. Funnily enough, my guitarist at the time had the same exact issue on the same model pedal. We both dumped ours and haven't looked back. What they do when we record is another matter, one I'm not privy too, but it the final result always sounds good.
^ this, but also a 10 band EQ (particularly the MXR one).
IMHO a hpf/lpf is a much more effective live tool. It helps me tame the room and eek out more volume from smaller rigs.
^ this, but also a 10 band EQ (particularly the MXR one).