I've just had Barney done for this very reason.
Barney had been fine with other dogs, male or female, neutered or not until he hit six and a half months. One night at training he decided that the dogs he'd happily played with for weeks had to be snapped at.
Quite frankly I was mortified, its not something I've experienced with Max. There was a small incident prior to Barney's snapping which could have set him off, so I arranged with the trainer to take him into a different class later that week to see how he behaved with a different set of dogs. Well it carried on. If they went near the treat bag, if he felt like it, on one occassion he was having a cuddle with another owner and his dog came to say hello and he snapped at him.
He'd started marking on our walks a couple of weeks prior to this which I think is hormonal too.
My trainer said he was being a stroppy teenage boy. It started to happen just when his hormones would have started to kick in, so I thought that this could well be a hormone related problem. I really didn't feel like I could wait to see if it stopped after his adolescence, I have often been asked if he's nasty as he's a red cocker. He's not nasty at all he's a lovely boy who adores cuddles, and I would just hate if it if people thought he was nasty.
The following week at our normal training session, the snapping continued so I booked him in for his castration the following week.
Its now two weeks after his castration. He went training last Thursday and he didn't snap at all. I know the effects of castration are usually seen 2-3 months after being done so I don't know whether its had an immediate effect on him or he was just in a good mood! However the marking has stopped totally for a week now. So maybe it has. I'm just keeping my fingers crossed.
For Ruffy I would say do it, unless you thought its a fear aggression, which you've ruled out. If you think its a hormonal thing then I'd do it, and sooner rather than later. The way I thought of it was that Barney obviously wasn't happy, I was stressed about him acting like that, he picks up on that which makes him worse. The options of keeping him on lead or muzzling him isn't what you want to do really, so if the vet and the behaviourist think its something that will help, does Pete have a leg to stand on???