We didn't have Reggie or Smokey neutered until they were older...and they've always marked in the house, Smokey was especially bad. Actually we have to keep a diaper on him constantly now because he'll just lift whenever, but I think that's more to do with incontinence.

It's always awful taking them for walks, because of the constant leg-lifting. It's gross. I had Nebo neutered at 4 months, and it's really curbed all of those things. He even still squats most of the time, and doesn't mark his territory. When he pees, he does it because he has to go, not because he feels the need to mark every friggin tree.

I could never have a dog that wasn't neutered...

Honestly, breeding is your choice of course, but, as others have said, the earlier you get him neutered, the more likely it will curb this habit.