I am running Ubuntu 16.04 LTS.
As far as I can see, in Ubuntu at least, the Ubuntu Display Settings Command handles thing like Multi Display and resolution etc.
In terms of fan temperatures etc I am using a command line to monitor GPU's (Two R9 Nano's).
I am seeing good benchmark performance and gaming stability but I was hoping to see an AMD Crimson ReLive type driver interface.
Since AMD Crimson ReLive GUI is built on Qt it should be "easy" to port the GUI to Linux, Disable buttons that don't work and at least have a starting point for a GUI.
RE: "I wouldn't expect something as comprehensive as Radeon Wattman on Linux"
I would and did.
GPU Passthrough to Virtual Machine on Linux is here to allow running Windows OS as a virtual machine for legacy reasons.
Vulkan seems to give great performance and MultiGPU support in Vulkan is on the way.
Ryzen Processors do not have built in GPU.
Seems to me, would make sense for AMD to work on providing better GUI interface and make sure GPU Passthrough setup is automated and
Vulkan MultiGPU support works as soon as possible.
With this, I predict many Windows users would move to Ubuntu very fast.
The move to Ubuntu is happening anyhow where I live, not just with people who work IT/PC technology either.
Many Windows Users I know have decided to throw in the towel with it and go Linux.