1) Read the CAP release notes. Yes, it can make performance better and take care of issues with certain programs.
2) You would have to ask the AMD driver team or Valve on that. It's not resolved for me yet, but it doesn't bother me as I don't need the overlay when playing this game. From what I can tell the overlay is not getting synced properly with CrossFire causing the flicker.
If they game plays fine for you now with zero issues there's no real reason to get the new CAP. Use what works.
1) Ok thanks. I know what CAPs do; I was asking more for your personal opinion and experience with any improvements you might have noticed as we're both using Crossfire and playing the game in question, not so much what the release notes say they do. If you haven't noticed any improvement or difference, for example how doors highlighted by Jensen's yellow vision seem "hazey" when they're behind whatever passes for DX11 fog in this engine, then that's fine.
2) Ahh I see. The phrasing of your post made it seem like the performance issue caused by the CAP was the overlay flicker, and that you resolved it somehow, even if its source wasn't the CAP alone. My mistake.
A bit of context from my viewpoint is that the Steam overlay usage in DXHR has been surprisingly well integrated, even to the point of how the game operates. For example, I've personally noticed that when DXHR is loading a level, it still acknowledges Shift-Tab input to pull up the overlay, whereas a lot of games will either ignore or outright disable overlay activating input when loading a level, unintendingly defeating the purpose of it (ex. Friend msged me while loading? Oh, I can't reply until the game says so?).
Also, once in the overlay, when the game is finished loading the level, it
waits for you to exit it and return to the game before rendering the level, thereby not having invasive music or visuals loading into your VOIP convo or your watching a youtube video.
It is because of this I'm more interested than average of any overlay issues in DXHR, since they've made so many appreciated strides in integrating it with the game.