Not a whole lot to say that hasn't been said already. I wasn't able to demo any comps before buying, and went with this based on good word of mouth and price.
I find it to be a pretty transparent pedal, in the best possible way. It acts a lot like a boost, but with the added benefit of evening out the sounds and adding that elusive "punch." My Ric has a set of almost totally dead strings, and the Opto Stomp made them sound about 1/2 new. I can't remember if this is supposed to be a "true bypass" pedal or not, but it sure sounds like one. There's no nasty CLICK! when they're engaged either. It plays nicely with my Truly Beautiful Disaster, as long as the
TBD comes before it in the chain. I haven't tried the comp in the
TBD's loop yet.
I bought two of these things (good deal on evilbay) to use the stereo output of my Ric into the dual channels on my SVT-VR. That combo alone has always been what I've heard in my head, and the addition of the comps has made that +5 awesome.
All that being said, I'm now interested in a more wild and squashy comp to possibly compliment one of the Opto Stomps.
Time to start saving up and time to start rereading Bongomania's compressor site again.