I went with the FS-6 with mine. The Roland already has the looper and the footswitch has to be cheaper that a separate looper. If you outgrow the Roland loop capabilities, you can use the footswitch to control the other effects.
I played 125+ looping gigs last year & couldn't have done it without the Boomerang III. If this isn't your need, then maybe the Boss might work, but I sold the Boss RC loop station years ago and glad I got rid of it.
yup...also, if you have an ipad, you can use teh FS-6 to move the pdf pages.
Ah pity, I already have the pedals, shame they don't sell the unit on it's own.
"Wayward, check out the Manitoba Hal stuff, he uses loopers quiet a lot.