It didn't affect my little Rex one bit! Glad to see another pup with the name Rex - I LOVE the name.
I had my Rexy neutered at 6 1/2 months and he is 13 months old and as slim and trim as can be. He doesn't mark - unlike my un-neutered Rowdy
He is a lovey dovey and I am glad that I had him neutered.
He and Rowdy are brothers from different litters - Rowdy is much more high strung and into everyone's "business". Rexy on the other hand is very laid back and easy going. I don't know if neutering Rexy is the reason, but I am glad that I did it.