It does compression and doesn't seem to cause any issues or tone changes in the process. I haven't given it a thorough workout, though, since I use a compressor before the ToneX, then the ToneX compressor is set to post-effects.
I hope they'll offer the option to audition amps and maybe buy individual models. I'm not going to pay $100 for 150 models, of which I would use 10 at most.