Right now I am mining haven with 1.68 using gpu:
1. Asus rog rx 580 8gb ==> 1.7.0 lower hashrate (1010 vs 1050)
I had the similar issue with my RX580's 8gb, 1090hr with 1.6.9 vs 1050hr with 1.7.0...after a while I noticed that the "fragments" wasn't set the same as in 1.6.9. After setting the fragments manually to 64 i got slightly increased hashrate to 1138. Also noticed that 1.7.0 version needs more time to reach the highest hashrates.