I just got done trying this set up and loved how it played as well. Regarding your question, I was able to get about 19 hours before I sheared it on the BH mishit. Notching in the mains was 40-50%. Playability was still good with string lock-up being very minimal on a modified CX 200 Tour 16*19. I think I probably would have gotten a couple more sessions (4 hours) from them if they didn't break.
At one point (~15 hour mark), I thought things had fallen off the cliff. Control became difficult and launchy. My overgrip was also worn so I was gripping the racquet tighter than normal. The overgrip change brought playability back to life. In fact, it was playing particularly sweet (At least on the FH side. The BH was problematic. Sheared 2 sets back to back...haha.) before breaking. Power, spin and predictable launch were firing on all cylinders. My hitting partner was taking a beating on the other side of the net...haha.