Yes, the ARX is a gimmick.
It is comfortably and technically the worst AR in the game.
It does some things very well, but those things can be done better by different weapons.
I like the appearance of the ARX and it has very nice irons - otherwise the Honey Badger is superior, just how much, depends on just how good you are with it.
If you want the properties of the ARX, the FAD offers them and more - FAD has a slightly shorter 3HK, but that is all the ARX has, it offers nothing else at all IMHO - note I have gold AR's, and 13+ days played.
The SC-2010 is also outstanding, extremely accurate; that the damage drops off over range should be inconsequential because the gun has very little recoil. VERY little recoil.