Boomer humps more than Duke does... Well, Duke never humps. Usually he goes for really crusty, old female dogs. If they are decrepit and feeble, they're game. He loves 'em. I don't let him get past the flirty, tail up, bouncing around though. He will posture with other intact males, and gets charged by other (neutered) dogs. That's pretty much all i've noticed to be a consistent "intact dog problem". There's never been anything not controllable. Both boys mark everything outdoors. Never indoors.
Duke is actually less tolerant with other dogs than Boomer is, and he's been neutered since he was 5 months old. He isn't aggressive, he just tells dogs what's up. He'll play with polite dogs, but he growls at rudeness. (paws to the face, humping, charging and body slamming) When I get another male dog, he'll keep his balls until there's a good reason he shouldn't.
Duke - 3yr old Labrador Retriever