It's a neat option, but not for rescues IMO. Well, not for the average rescue anyway. I'm not sure it would help with the hormone issues. Also, neuters are not really much of an issue to do to begin with... They are really easy as far as surgery goes. If vets would just stay reasonable in costs, neutering would be so much more sensible. Spays, on the other hand, tend to be more complicated.
I do like the idea of something like this for the fools who are attached to their dog's "manliness". But there needs to be a clear way for people to know they are neutered - in particular for the show world. While I might not always agree with dog show rules, I am against breaking the rules with something like neuticles, or this. I'd rather just see altered dogs allowed, or altered classes... But that's another can'o'worms