I use an RC-20 on-stage. For me it was a toss-up between the RC-20 and the Boomerang. I didn't really need all the bells and whistles the Boomerang offered (I just wanted something to loop on the fly), and with the ability to store 5 minutes of looping, I went with the RC-20. Also the fact that in a drunken stooper, a two pedal stomp box is easier to manipulate than the 5 on the Boomerang...YMMV
BTW...I'm presently not gigging (for a while anyway due to the new baby thing), so if you're anywhere near CT and want to borrow (It's not for sale) the RC-20 to check out, let me know.