[6BL Bird-Dog]

From experiance I got various results with different card combo`s single and X-Fire.
1x AMD Saphire Toxic 5870 Oc, poor frame rates and micro studders,had to use medium settings .
2x AMD Saphire Toxic 5870 Oc,best ever performance when the early patch release enabled X-Fire,Max settings, good high frame rates and only the microstudders low.Ruined when a small patch was bought out within hours because of graphics anomolys with Nvidia systems.
1xXFX HD 7970 Black Edition,Improvement on single 5870, but running at Very High in game settings made little difference ,frame rates improved slightly.
2xXFX HD 7970 Black Edition,with both last Alpa and Beta patches more or less the same as a single XFX HD 7970 Black Edition performance slightly improved at highest settings.
I tested the same cards and setups on the rig in my sig and did compare performance with RoF and iL2 1946 ,the latter of which does not have X-Fire support.
In Rise of Flight as I Improved my Gpu hardware I was able to increases my quality settings with also an increase in FPS .The 2x AMD Saphire Toxic 5870 Oc performance was slghtly slower than a single XFX HD 7970 Black Edition.
2xXFX HD 7970 Black Edition runs fluidly with all settings at max with the exception of AntAliasing which Inever run above 2x as it murders the fps in ROF.
iL2 1946 ran maxed out on all combinations ,seamlessly on 2xXFX HD 7970 Black Edition, with the Average FPS limited to 60mhz(my native screen res),but max frames are almost always over 1000fps.
The Clod dev team hit the sweet spot once for me on X-fire but have never unfortunately got close since.
In Cliffs of Dover`s present state apart from increasing in game video quality settings performance wise X-Fire is not functioning in anyway near to the Early X-Fire patch release which on my system was awesome compared to any patches before or after,the textures looked much better then too if a little bit too bright.