I'm doubting it is 0.6, since no weapon in the game has that kind of recoil to both sides. Only the absolute worse have it to one direction only. And exactly, can compensate for vertical, the weapons with high horizontal recoil usually don't have high vertical recoil (PKP and M240B as exceptions), so running a Compensator on those high ROF weapons makes sense, since dropping their moderate vert recoil just seems silly.
Not that thats a horrible combination, just if I was looking for an LMG accurate at range I would go with the QBB instead and relegate the M249 or MG4 to more of a Medium range engagement weapon with a Compensator and a Angled grip. That way I knock off some side to side recoil while removing that 1st shot recoil (since thats the hardest recoil to correct for, after the 1st shot its much easier). And then just make sure to ADS and rip people down. Though different strokes for different folks, I also love the PKP for range, I run Muzzle Brake and Angled on that since she has some kick and just 1,2, or 3 round burst it and with it's high damage it just tears people apart and doesn't get too far off track as long as you let off the trigger.
I really haven't been a fan of the HBar in BF4. In BF3 I ran it on almost every weapon, but now it doesn't increase your Damage Drop Off Range. Though it now doesn't have a Hip Fire Penalty either. I'd rather have a longer damage drop off and that hip fire penalty back. The increased recoil just for some better ADS pin pointing isn't worth it to me. I'd rather have a more controlable weapon, then I'll put the sights on them and let it rip, sure the bullet might not go into the chest I'm aiming at, it might be right arm or left arm, thats fine by me.