The 16.5.3 update has solved the Crossfire flickering within The Division.
However, when Crossfire is enabled there is a pretty big drop in performance over a single GPU, there is constant stutter and the game is unplayable. In the open world it gets so bad that you'll walk for a few meters on 90 fps, stutter around for a few seconds with basically 1-5 fps and then get normal fps again.
On a single GPU the game plays fine.
My system specs are:
Gigabyte G1 Z97 Sniper
2x Sapphire R9 290 4GB Tri-X
Crucial Ballistix Sport DDR3 16GB (4x4)
Samsung 850 512GB SSD
Netzteil EVGA 850W NOVA 850 G2 (80+Gold)