I can confirm with Claymore 11.5, I was getting about 31.9 MH/s on my 6 x RX470 rig with custom BIOS, but now I'm getting 27.6 MH/s about 12% less. Seems more consistent in terms of speed. The power draw is now lower too.

Also my rig froze today after a 10 days of work. I will keep the new drivers and see how the rig will behave in the next couple of weeks.

Last minute correction: changed dcri to auto detect and I'm getting 31.9MH/s again! Power draw increased a bit...