Well the 50 and 60 were just made up numbers. Honestly, I the difference is potentially much greater. Berserk alone can cause me to do 20 more than my normal average.

I'm currently wearing the best acc build you can have without having HQ snipers and a PCC and I'm just edging into 80% accuracy. The parser clearly shows that I do better with more acc than with less. The fact that I was doing more damage with 240ish Atk and 80% acc than I was with 320ish Atk and 60% acc should say something about the importance of Acc > Atk.

The fact that acc gear isn't cheap is all the more reason to focus on it. Crossblades probably won't have 2xWoodsman's at 40. Losing 10 Acc from the ring slots is will put a big hit on his acc, so I think it's important to focus on as much acc on other slots as possible.

Wearing every bit of Acc+ gear possible, you can still get a very healthy balance of Atk/STR on the slots where no acc is available.