I had a RX 470 rig that was unstable on 1.6.2 (stable on 1.5).
This rig is now stable on 1.7 (overnight) in default pci-mode (2). I did not check other modes.
Overall speed is improved in 1.7 vs 1.5, so I am happy.
The rig uses about 50-70W more, though, on Ubuntu Linux 16.04 (about 6-7%) with speed increase of 6-7% as well (vs 1.5), so make sure you have power reserves if you switch.
Thanks for an update, Optiminer.