The GSP has a really short coat. However the lab isn't known for a having a long coat such as a golden, but its the weight that gives the lab the disadvantage in the upland fields and on warm days.

And as far as hard mouthing small birds, I would say you would have a better chance with a GSP than a lab, granted any dog will hard mouth if the owner doesn't know what he's doing. A word of advice from the get-go, do NOT ever play tug-a-war with your dog, do NOT snatch the dummy,bumper,bird,etc. from your dog quickly and lots of force. This is where you can CREATE hard mouth. Instead say "out" and push the dogs lip against its teeth behind the bird/bumper and the dog should release. After enough of those lessons you shouldn't have any problem.