Honestly, the high rate of fire is what makes it such a great suppresive fire weapon. Especially when fired in bursts from a distance, the bullets spread over such a wide area that you can keep a whole squad down. It's not terribly inaccurate, but compared to other MGs it's pretty low on the list.
Mobility wise, I was referring to the full crew configuration, bipod or tripod, spotter, loader, gunner, etc. Common sense would say if you were all set up (especially with a tripod) and had a hot barrel, you would abandon the gun, rather than take the gun off the tripod, swap out the barrels so you don't scald your hand, try and organise the ammo, and all that other good stuff before running away. This was the same with a lot of machineguns, actually.
When in the bipod config, with minimal crew (gunner and loader), then yes, mobility is very good.