I also experienced troubles upgrading two RB260s to 1.17 (in my case they were GS units.) See http://forum.mikrotik.com/t/bricked-two-rb260s-upgrading-to-swos-1-17/107165/1
Judging anecdotally from these reports I think there is a real problem with 1.17 on certain RB260s (I had no problems upgrading RB250s to it.) To be on the safe side I’ve decided to skip that release for my other RB260s.