...well, when I'm on test/tren or the like creatine is useless. I can only speculate that if 1-AD and 4-AD are powerfull enough to add 10-20 lbs of mass then creatine will be equally useless. Most steroids increase mitochondrial proliferation, and in turn you have alot more ATP floating around so PC isnt going to add anything noticable.
On the other hand, creatine is cheap and it certainly wont hinder gains. I say use it, just in case...
Good luck on your cycle.