I have 290x CF. After I installed 16.4.2 I don't see any more flicking, however the performance is like worst than running with a single card.
Please install Crimson 16.8.3.
I had the negative Scaling Issue on my system i74770K, GPU1 = Sapphire HD7970 OC 6GB, GPU2 = Sapphire R9 280x OC 3GB.
Note my cards are not on the Crossfire Compatibility chart.
For me negative scaling is fixed since Crimson 16.8.1.
I get FPS improvement of 1.42 in the Division on Ultra and can run at 56-60FPS at 1080p.
Hope this helps.