I used various Boss loopers for several years, the RC-50 most recently. This past summer I switched to software-based looping and am thrilled with the results. I'll copy from a post under an earlier thread...
I am using a MacBook Pro, 2.8 GHz, 4GB Ram for both recording a looping. I run Pro Tools LE v8 and use an mBox II as my interface. My looping software is SooperLooper inside of Live with a boatload of plugins.
Portability is important to me and I don't need a ton of buttons at my disposal. My controller is Tech 21 MIDI Moose, MIDI Solutions Pedal Controller, and Boss FV-500L which I chain together into the MIDI port on the mBox II. (There's an interesting post on the Ableton Live forum about using a Line 6 FBV Express MK2 via the USB interface as a controller. Portable and pretty inexpensive. That and a small audio interface could be interesting.)
It all works great, I've had six loops and a dozen plug-ins going simultaneously without taxing the setup. This is working well for me and what I do. Your mileage may vary.
More about my plug-ins on the gear page at
http://www.lorenclaypool.com.
P.S. - I am using this setup with acoustic, electric, baritone electric, fretless electric, lap steel, baritone lap steel, touch and synthesizer guitars.