I have (had, actually we just had to put the old guy down a few weeks ago) a lab cross, and we also have a golden retriever as well. The best of both worlds! Long and short! We have a furminator and while it worked on the lab I would say that you really wouldn't get your moneys worth out of it, it is not worth the extra expense for a lab, one of those looped serrated steel rakes works wonders on a lab coat and you are not going to see much better with a furminator.
Now the Golden on the other hand, WOW, I could brush him and use the fur I get off him for batting in my quilts! It just falls off him with the furminator! Mind you though this 'brush' was not intended for 'everyday' use. It is a once a week sort of thing while using a slicker brush for brushings in between. You can rob your poor doggie (or kitty) of his nice warm undercoat in no time!