I had mine tinted, though I am not sure what kind of film was used. It probably says on the lifetime warranty paper they gave me. Anyway, I have not had any loss of reception that I have noticed, but I really can't compare a before and after since I had this done in the first week of owning.
I would suggest having it done; it really helps with the heat and other sun damage. From what I understand about window tint, the factory tint does not block UV rays because it is just "painted glass". The tint film will block UV rays, keeping it cooler and adding protection. I definitely noticed the heat difference last summer! Plus you get the added security of not being able to see in.