Volume issues were why I got rid of it. I would set a preset to a decent level, or what I thought it was, and at both gigs I used it on, the sound dropped a ton, and I raised it manually, but still wasn't ever enough. I don't think the compressor had anything to do with it, just the Mono Synth. Get a C4, much more sonic options for not much more money.
Have you played the C4 with guitar at all? Saw a review saying it's not brilliant when played polyphonically. Ideally if I go for a more premium synth pedal I'd like it to be as versatile as possible.