Change daycare?

I am considering changing daycare for my son. His current daycare is OK but not very good. It accepts children from 3 months old.
He has been in this daycare for almost 1 year and he is happy in there. He likes the classmates and they are good friends. He is 2 and a half now and he is going to be 3 this fall. The teachers are potty training him and he is doing well. No accident yet ( 2 days in underpants only).
There is a preschool with very good reputation in my area and that's the one I want to send him after he is 3 (they only accept kids 3 and older). I know quite some friends in my community sending their kids there and they all recommend it to me. It's clean, organized and provides excellent care. And it makes sense to find a preschool for a 3 year old. It should be a better place for my son.
My only concern is that he likes the current one and he likes his friends. Will he be sad if he leaves them? Or will he have new good griends very soon and be happy again? I just don't know how long it will take.