Like yourself I received an A2 replacement unit with 1.12 fw installed. I took a gamble and flashed to 1.15 I had a few issues early on, mainly user error. For the last couple of months It has run flawlessly. I've pondered flashing to 1.21, but I think I'll stay put at where I'm at. This has been my experience and by no way am I endorsing or approving anyone else to do as I did.