I know this is an old thread but I've also been looking at the Boss RC-2 and RC-20XL. It looks like they both pretty much do the same thing but the 20XL has the additional input for a CD or MP3 player... but, unless I'm mistaken, the RC2 has a bunch of drum patterns that you can play to whereas the 20XL just has a metronome.

Since I'm just a beginner I'm leaning towards the RC2 because I read on one thread that you can overcome the inability to plug in an external player simply by recording it into the device, unplugging the device and then playing the tune as a backing loop... or something to that effect.

Itsmesilly, which one did you end up going with? Are you pleased with the decision that you made?