Here is my opinion on this. I would only want to keep an intact male around IF I planned on showing him, is that what the plans are for this pup? If not, I wouldn't go into this partnership. It is quite common for show dogs to have co-owners and have an arrangement like this. If he isn't going to be shown though, there is no reason to breed him. No reason to co-own. IF he proves not to be show or breeding quality....I'd want a stipulation in the contract that says he becomes all yours.
Risks to not neutering in my opinion are too greyt to not neuter a pet dog. Testicle cancer can be a problem in intact males. Aggression can be another, especially to other male dogs. An intact male can be difficult to train and live with. If he smells a female in heat, he will do anything he can to try to get to her, which can mean going after your other dog, to going after you. Now, this doesn't mean any of this will happen. I've just heard horror stories from people who breed and keep intact animals together.
I do hope some other people who have lived with and bred dogs will pop in and let you know how this works.
-----
Melody/PHFasDog
Email me at PHFasDog

My furkids:
Shadow, Jadzia and Lyta.
Kira waiting the bridge.
Dogs come into our lives, and too quickly go leaving pawprints on our hearts, and we will never be quite the same again.