I have a Studiolive Series III and have the same issue with poor sounding reverbs.
I just want a good sounding reverb for a vocalist to use while tracking. The studio live series 3 reverb’s are not as good as any plug-ins that I have. Using plug-ins is not an option for me because the round-trip delay through the mixer and back out to the USB digital input has too much latency (even with small buffer sizes) to be acceptable for the vocalist. I really do wish they would produce a better reverb option for the studio live series III consoles.
I must say though, other than that I really am extremely happy with this console in my studio. It provides so much flexibility, and the integration to StudioOne in my opinion is stellar. I very seldom use my mouse on 3rd party plugins anymore. I just use the knobs on my Fat Channel, close my eyes and listen : ).