After many days worth of digging through forums and trying .ini tweaks, I have finally pinned down the cause of the water, metal and distant walls flickering when running Crossfire.
I noticed the flickering was most noticable in distant windows walls and water, and only affected items which were hit by sunlight and not the light from flames.
Lightbulb! Must be the lighting right? But there are no lighting tweaks, so I messed with the next best thing, namely the shadows.
I had already used RadeonPro to flip the Queue Size, this made things a bit less noticeable, but didn't fix the flickering completely.
I'm currently back on the default Queue Size, but this fix works with and without the Queue Size tweak.
Also delete any profile you may have made in CCC, and disable AA (bin/config/base) in rendering.ini just set temporal to false.
If you want SMAA you can force it through RadeonPro or Sweetfx 2.0+Reshade (doesn't work with 1.5 and the toggle doesn't work with either).
If you use RadeonPro for the SMAA and the game refuses to launch, just right click and disable API Monitoring and Auto-Detection.
Go to your 'My Documents/Witcher 3' folder and delete user.settings.bak (don't worry this is just the backup file).
Do this every time you wish to change a setting, or it will not be saved and the above file just overwrites any changes you've made.
Now open user.settings with notepad.
Scroll down to the 'Rendering' section.
And just change 'CascadeShadowDistanceScale2=' to a value of 1.7 (Ultra is 1.5 by default).
This changes the quality of the shadows rendered in the distance, and if your rig can handle it you should be able to go even higher.
Although I doubt that's needed since 1.6 left some very light flickering and 1.7 got rid of it all together.
Note...sometimes when entering the world the game may crash, happens about half the time.
If you get past this every thing is stable.
However since I can only speak for myself, I would like some responses from people with different GPU/CPU setups.
Just so people have some idea of where their settings should be at.
Please provide GPU/CPU info and off course the value you're running best at.
Other specs like game/driver/os version could also prove useful.
Mine are...2x 280x/fx8350 at 1.7.
Other Specs...Witcher 3 Patch 1.05/AMD 15.5 Beta drivers/Windows 7 Ultimate x64
In-Game every thing is on ultra except AA which is off.
I've also noticed the fps limiter makes the greatest impact on the stuttering.
For me it's silky smooth at 30 and slightly choppy at 60 but nothing major.
Hope this works for you guys/girls, and please take the time to report back if you get this working.
P.S. Sorry for the wall of text, but I though I aught to be thorough.
P.P.S This is my 1st thread on the AMD forums, so sorry in advance if this is in the wrong section or something.