I would go for it
I'd suggest to do it while Sadie is under for her spay. That's when most get it done.
It saves thousands upon thousands of animals per year. Personally, it just gives me an extra piece of mind that if he were ever to get away from me, it's easy to just scan him at a veterinarian. There have not been many reported complications with it, as far as I know. Some people don't like the idea of putting "foreign objects" in their pet's body, but I find it no different than a person/animal having to get a rod put in their leg for surgery or something.