I have seen half breed mutts out perform 3000$ dogs time and time again, I would not get hung up on a specific line but rather the type of lab, IMO being you lookin for an upland lab I would start looking for a pointing lab they are great retreivers but also point which for me is nice, I need the warning some times
I’ll chim in with a plug for the Brittish Lab. Mine is about 3 years old and I couldn’t be happier. Smaller (she’s about 55 pounds), mellow and affectionate, but she hunts very, very hard.