You should be able to get support on this but as I have found out its completely volunteer. They have five people working on updating the software and no one on support for their reputed 50,000 users. Only a poorly compiled set of instructions on what to do when it does not work, especially if your are mining anything other than ethereum.
Downloaded and installed V1119, it updated, I got it running briefly with XFCE desktop showing but now it does not run. It zips through a startup sequence but I do not get to XFCE desktop just a cursor top left so I have no idea what is wrong.
The RX 5xx series is not a rebrand. As far as hashrate goes - it will depend on the coin, memory-limited stuff like ETH probably will see no or barely any increase, core-limited stuff like ZEC should see a small increase.
New to this when you say memory limited do you mean ETH needs more memory, 8GB instead of 4GB ?