Nexus has a mod, released by CD Projeck Red employee, that is said to address some all around issues related to combat and I'm wondering what the community here thinks.
I can easily start new game after applying the patch and I suppose I could back up the unpatched game folder now just in case it causes problems.
What do you think?

Definitely not. It's a very radical overhaul of everything in the game, combat mechanics, XP, loot, skills, equipment. For second playthrough or later. The base game is excellent as it is and although FCR offers a few things that might be considered fixes, it is not a fixpack by any means.

If you play the first time with FCR you will really have no idea what the actual game is like. The manual and any info about the game on the net will also be completely useless to you. If you wait til second playthrough you will be able to appreciate things that were changed in the mod and whether you like the changes or not.