First I would like to say that I am against using the prong collar on Rory. That dosnt mean I am against or for it at all. I think it depends on the dog, his reaction, and what other methods you have used and failed with prior to trying the prong collar.
Rory did not respond well at all, yes she is a pit bull with a very large tolerance to pain, she saw a horse, took off after it, did not head to the prong collar and was left with bloody wounds. This all happened within 4 seconds, thankfully she was small enough to pick up so she couldnt hurt herself.
I feel that if your dog responds properly to the collar then maybe it is the right step for you and your dog. Please may I suggest using it in in conjunction with a verbal command. In the future he may learn to recognze that command and not need the prong collar. BUT please no matter what you do, don't leave him in the collar when he isnt walking like someone suggested. Part of the purpose is to get him into unifiorm walking mode, he should assume this mode when that collar is slipped over his head, not have it lurking around his neck at all times. Not to mention their is a great risk of it getting caught on something. If that does happen you would think they would stop pulling to stop the choking but its the exact opposite, they get scared and try to break free which can be fatal.
I read that you didnt want to try the other options because he is a growing dog and that could eventually be costly having to keep upgrading. The same could be said with you buying a prong collar and him not liking it.
Rory started with a harness, she reared up and just walked on her hind legs $18
Rory then moved to the nylon slip collar, she choked herself repeatedly $14
Rory then tried the chain slip collar-more choking $9
Rory then moved to the dreaded prong collar which cut into her skin making her bleed $24
Plus the visit to the vet for that $60
It took me until she was six months to fork over the $28 for a gentle lead and it was a god send!
It seems to have corrected her pulling, she hardly needs it anymore but I carry it with us just in case! Good luck with your big boy!