If you need a compensator on the AKU-12, you are doing it wrong. It's arguably the most tame gun in the game, right up there with the SAR-21. I see Levelcap and some others advocating these brake/compensator crutches as ways to 'tame' guns when most guns are flat out better than their BF3 equivalents and the recoil compensation is something you can easily do yourself. It's just not worth a 30% accuracy penalty on a lot of guns.
The only place I can really advocate using them is on LMG
http://cl.ly/0x2b3Z2Y2Z1Ls, due to the need for sustained fire vs precision fire. If you are really bad at controlling guns, anything with a ROF >750 could use one.