Not too experienced w/ fina, but I once took deca only, and I was a stallion. I'd say deca accually improved my sex drive. I guess "deca-dick" only hapens to some people.
If he has problems with his weiner just pm me and you can fly out every other weekend or so and I will take care of the problem. If that would be too much of a hassle you could try feeding him Cialis at 20mg EOD.