I got an RP-100 and it's perfect for my needs. However it might not shine in a live gig setting, but it could be done. Just have your song's tones (if more than one) stored sequentially next to each other so you don't have to jump from preset #2 to #30 in the middle of the song. It's proven to be very useful and versatile otherwise though...from noise gate and compressor, to delays and chorus. Also Digitech has a user patch library for certain tones I browse through sometimes, some are great, some aren't. Here's the library for the RP-50
As for Zoom, I don't have much experience with them except a drum machine (which is kinda hard to use and has yet to prove its usefullness), but I haven't heard anyone ever say they're good, quite the opposite.