neuter!!!
There are many behavioral advantages behind neutering, along with no marking, reduced risk of testicular cancer (I think if you spay your girl dog the cancer risk is reduced even more drastically). Also, if you want to be nit-picky, you don't have to look at a pair of balls when your taking your dog for a walk
If someone wants to use him as a stud you'll get a nominal one time fee I believe, but it won't compare to the cost of training for behavior or vet fees for cancer, or looking for him if he smells a dog in heat and runs away.
neuter!!
