[guitardave]

My ref6 has sounded great from hour 1. Of course it is getting better with use, now about 300 hrs.
I had the 2 mk2, the 3, 5, and 5se previously. Each was a clear improvement over the previous model, to varying degrees. I think one reason people feel the models are unpredictable during break-in is because they reveal flaws you never noticed on less revealing gear. Every song reveals its recording venue with the 6. If a recording is compressed, or edgy, or rolled off, it is revealed in stark clarity.
I am not saying these pieces are not a bit edgy when new. I do notice that, but only very slightly and not after about 50 hrs in my case(s).