Thanks for answering. I use SMOS and Cast-XMR is not currently supported.
Claymore 11.3 gives me the best speed so far at ~785H/s using stock settings
xmrig-amd-v2.6.0-beta1 with --opencl-launch 896x4 gives ~710H/s

My cards are clocked at 1280/2000.

Any ideas?