CC and SR equipped Scouts can be good for holding onto objectives, since they're cover save makes them difficult to kill. The SR rend, so you can actually do some damage with them over the course of a few turns. Also, the pinning test can stop an enemy unit from closing on a objective.
Moreover, the pinning keeps the unit where it was, which means the Scout can do even more damage to it. Against Tau or Guard, this is brutal.
Something else to mention, Scouts work well with a TF Cannon. The cannon comes with a full Tech-Marine, and he can give is cover-reinforcement to the Scouts. This mean 2+ saves for the Scouts.
Basically, fire the Cannon, fire the ML or HB, then fire the SR, and hope the pin something. Don't fire them first, because if a unit G2G, then it'll get a cover save against the HG and Cannon (Also, there will be less units to cove with the templates).