I would be interested in hearing what you see when you watch the labs work, vs the gsd.
I have to say at this point that I am not a lab fan, I love all dogs but labs are not one of my favorites to work with or around. I find myself for the first time disagreeing with Nancy about labs on only a few points. 1st the labs I have seen can be quite crate agressive and territorial, especially female labs, whereas most of the GSD handlers I know will NOT tolerate this behavior. I agree with the lack of social manners that most I have seen possess. Most shepherds I have worked around are more reserved, but not necc. agressive than the labs but each time I have seen any lab vs gsd agression I have witnessed was initiated by the labs. I agree that labs are much less reserved with humans than the GSD's. Watching a lab work is watching a very happy dog, but some are so spastic that its hard for even the handler to read the dog. A gsd is almost always readable, infact I have never yet met a GSD that I cannot read in either SAR work or any other behavioral conditioning I have been involved in.
Both the labs and GSD's that I have worked with will range beautifully, the difference for me is that (being a herding dog) the GSD returns to check on its "herd" being the handler and flankers whereas the Lab just goes and does not circle and return.
Other than these minor differences in observation Nancy is right on again with advise given, especially NOT to do any Schutzhund work with your puppy. There is a wonderful book "training in drive" that is a Sch book but will work at increasing drive and focus, but SAR units will not look kindly on any team doing any bite or personal protection work. While I know that a dog that has been trained to bite ONLY when commanded to is safe, but is not tolerated at this time in SAR. I cant wait to hear how your puppy is developing and hope you will share more as you learn.