I own the Boss RC20XL and really like it. It is great for practice but I use it at times during performance with the band. One song we have plays an 8th note repeatedly, and lightly, through the entire song so I get that going and then go on playing the rest of the song. Mostly, I use it for practicing lead parts and scales.
The down side is that at times the Boss pedal seems to have a mind of its own. I press the switch for recording and all the sudden it starts playing a recorded loop that I made months ago. Not sure what I am doing wrong but I am pretty sure its my fault.
Here is a forum for everything between the guitar (here) and the amp (there). If you want to know about cables, effects pedals, multieffects, noisegates, line drivers, phasers, distortion post your questions in here.