I'm pretty good with a wrist rocket. Did take a guy down at about 50 yds with a sturnum hit.
Caution when tryin to learn to use a Sling.....make sure you are in the MIDDLE of a good clear area. Nuthin like takin out a car window Behind you. Specially if it isn't your car.
I don't think either is good for CQ defense due to the time required to deploy.
From what I have tried, Glamdring is dead on re the practice required.