My Thief results running a 8350, R9-290, 16GB Ram, 14.3 beta drivers and 1.3 Thief patch:
Min 31.7 55.6
Max 97.6 119.6
Avg 49.2 81.0
Nice improvement for $0. Well done AMD. I look forward to future driver releases, patches and more games with Mantle support
With regards to driver installs I used the uninstall all AMD software option, rebooted, installed the new beta and restarted with no discernable problems yet.
It's early days but so far it looks very promising.