Very limited experience with loopers here, but my current dedicated gear budget is for a looper, so I'm in the market. I work with a duo, and my priority is ease of use in the live environment. After perusing loads of online references, the concensus that I took away from my research is that the Boomerang is far and away the simplest format for live use; this opinion was nearly unanimously accepted.
So, Boomerang it is, and I gots me some cash to deal. The problem is that the product is in a state of purgatory - the company actually does not offer a current model looper, to my understanding. Prototype designs of the III Phrase Sampler
have been floating around for, well, quite some time, and afficianados have been put off by the repeatedly delayed "release dates". That aside... while I'll bet that the proposed prototype certainly addresses concerns of bonafide loop freaks, the format looks unappealing to me, as compared to the butt-simple format of the "Plus" (the most recent actual production model). The biggest buzzkill for me personally with the prototype is the lack of the global flywheel volume roller, which is a huge practical selling point for me.
I guess what I'm saying is that I'll likely pop for a used, recent production model Boomerang.