I bought one last week to use as a backup, spare, rehearsal rig etc. I took it to my steady jazz trio gig (tenor, guitar, bass) this weekend:
I used my Fishman Platinum ProEq for the tone shaping, with the Line6 as "flat" as I could figure out, and with Drive and Compressor both off. The Rock preset was probably (and ironically) the best match--rounder on the bottom, nice definition on the high end--though Clean was OK too. Plenty of volume for my gig, though I wish there were more clean preamp gain available (drive gets gritty quickly).
I also wish there were a way to turn off the modelling and run it manually; I feel that I am still hearing some signal processing, especially at the tail end of a sustained note.
Generally, the tone was acceptable, though the E string was not as coherent as with my other gear. Even arco was OK
My conclusion: it is a very useable piece of equipment for $250, and I will find occasions to gig with it, in addition to rehearsals, backup etc.
(P.S. I was very impressed with the tone with my Modulus Quantum5. I was easily able to approach the sound and punch of my GK rig. Surprising.)