Ubuntu 16.04 - fglrx is deprecated - is "radeon" driver OK these days?

[epixoip]

I think for amdgpu to work with OpenCL you need the "hybrid driver" aka "amd gpu-pro", basically the open source driver + AMD's binary blob.

A third option is to just stick with Ubuntu 14.04 LTS, it will continue to be supported until October 2019.