I owned the pre-USB RC-2 version of this same pedal and sold it on Ebay after a few months. Two months later Boss came out with the RC-3, which has USB. In the mean time, I got a JamMan Stereo. After a couple of performances with the JamMan Stereo, I gave it to my dad because I didn't like the "click" of the switches, or the crappy MS Silverlight software that they make you use. Terrible stuff.
Somewhere along the line, I picked up a Line 6 DL4, which is pretty sweet, and I will probably never sell it. But I still wanted more.
I really wanted the quiet switches that Boss offers, and USB capability. So I thought the RC-3 would be worth chance. I really wanted to like this pedal.
Boy was I wrong.
Look, I'm a fairly technical user. I play a lot of different instruments, run a lot of different software, and have experience with a lot of different pedals. I perform in multiple genres, and play everything from blues/folk rock to electronica and jazz. But when it comes to looping, I want a low-overhead, easy to use device and lots of intuitive creative possibilities. Sadly, the RC-3 fails on all these points, despite what you see in the ads. It's almost made for Ebay resale.
The RC-3 is practically useless without an additional 2-switch footpedal (the FS-6). The RC-3 is practically useless for live, on the spot creation because there is so much stop/start required that just KILLS creativity. The RC-3 is practically useless unless you are going to pre-record your loops. You can not save without stopping the flow of your music(!).Even the JamMan had this figured out (though it required stepping away from the instrument and touching the pedal with your fingers).
I had some fun tonight with an acoustic bass plugged in to the RC-3, overdubbing onto a single loop. But that's about it. The fact that the RC-3 doesn't save your preferences for auto-start after power down is sad. I had a lot of trouble getting the RC-3 to STOP replaying my loop when all I wanted it to do was play back the first loop (the RC-3 goes into record mode *immediately* after recording your first loop). Again, just sad.
As a practice tool, the RC-3 can work fine. But for live use it is a liability at best. The videos for the RC-30 look a bit more convincing, but I'd say at this point unless you are willing to invest in one of the larger Boss loopers, you should pass on the smaller units if you want serious features. Even the TC Electronic Ditto X4 looks better.