welcome to the forum, tim..
you'll get lots of love for th 2880 around here.. it's the unofficial 12k mascot. in fact, i don't even think you're allowed to post on the forum unless you have one
i have a 2880, but not a boomerang, so i can only speak for the 2880... in short, i love it. the fact that you have, of course, unlimited overdubs, but also on 4 tracks, makes for great mixing potential. and how you can record pitch and reverse changes into the loops and stuff makes it a great compositional tool.
drawbacks are few... the main one being no undo, and, you do often get a click, as with most loopers, when the loop turns over. especially if you're looping droning material. would be really nice if it had a crossfade on the loop point.
some day someone will make an ambient looper with a user-controllable crossfade of up to like 10 seconds, that would be amazing.
i use my 2880 without the food pedal, but i'm also not a very accomplished guitarist, so i sort of pick and ebow my way through loops and find i can get by without the controller... but, yes, it would probably be beneficial if you were sitting and actually playing the guitar.