This not only allows you to have an instant Snipe every 6 seconds but you get a pretty much permanent 20% ranged defense bonus. Not too shabby I'd say. So as you can see Snipers ARE very much mobile in MM spec. I move to a new position every 6 seconds.
It is sort of funny. A lot of the toys that Mercs are asking for are already available to Snipers, the ranged class that actually is functional.