I love me some M60 but I to share the same gripe a lot of others do, the slow movement. Although I've recently been more into the MK46, the second game I used it I dropped a moab so I suppose that makes the gun more appealing.
For any LMG I'll use the following setup:
Ext. Conditioning, Assassin/Blast Shield and Stalker.
C4 and Flash Grenades.
Strike package: Specialist
Marksman, Recon/Blind Eye and SoH.
I always use Specialist as with the defensive playstyle I usually play with LMG's, it's not too hard to achieve the bonus. To me that extra mobility makes me feel more comfortable to be a little more aggressive and move around a bit more. Imo the mobility
of them should be equal to the more mobile snipers like the MSR and L118, at 90% movement speed instead of the sluggish 80% they're at now. I can't see it making them OP or anyone really moaning about it, not any more than they do the snipers anyway.