We had our yorkie micro chipped and spayed on Aug 7th of this year. She did great .... we have Avid chip .... I personally feel better that I will have a greater chance of her being returned to us, in the event she gets out the door on her own. Also, we did not put the Avid tag on her ... just in case someone finds her and is reluctant to take her to the vet because of this. She is tattooed as well. Personally, I think you have to do what you feel is important to you. Good luck on your decision.
Cheryl & Mandy