How to gauge chicken breast doneness on grill pan?
At my restaurant, I'll cook a chicken to 160 and let it carry-over to 163 - 165. 165 is only the highest you should ever go with chicken. I do this just to stay within compliance and to be honest if someone asks me if it's "all the way done." It really messes with the meat, though.

At home, or when I'm cooking for friends and family, you bet your ass I'll pull that bird off at 150 to 155. As you noted in your post, that is when it's cooked all the way through and still retains a pleasurable texture. But the idea that the chicken has to be cooked to hell has been beaten into us and never really challenged. 165 is the temperature at which salmonella is effectively killed off when you're cooking relatively hot and fast. These guidelines were also made at a time when food manufacturers were hellhouses, unsafe and unsanitary. Nowadays, by and large, the reality is much different. There's still risk, but as long as you're not serving chicken tartare, your risk for getting sick off chicken cooked at 150 is extremely low. (That said, if someone has a vulnerable immune system, it's better to just take risk off the table and cook it "all the way.")

One other thing: one thing that will help with this issue, and acts as a safety net just in case you walk away from the stove and your chicken does get overcooked, is to dry brine the chicken. Don't do a wet brine for chicken breasts, because it ends up waterlogging the meat and whatever you cook will be rubbery as hell. Wet brines should be reserved for WOGs or other whole carcasses. Dry brining is basically doing a short-term salt cure. A 1/4 teaspoon of salt on both sides of the chicken and let it sit in your fridge for an hour or two. The chicken breast will then be more forgiving and still stay a good piece of meat.