Not everyone eats burgers that are pink. I am one that perfers a completely cooked burger. I do agree with Bigabyte that if you grind the meat yourself, then you can cook to an internal temp of 125-140. IMO, store bought ground meat has to be cooked to 160-165.
I have smoked burgers before at 250 until an internal temp of 165. They were a great color, juicy and flavorful.
Bubba Keg / Stumps Baby / Super Fast Yellow Thermapen / Lodge Cast Iron Grill / Smoke Vault