I live in Massachusetts and have a MA permit as well as the Utah non-resident permit.
The group of states that honor the Utah non-resident permit does not include MA or NY... or fellow northeast states of CT, RI, ME, MD, and NJ.
When driving through these states, simply keep the unloaded firearm locked in its case and locked in the trunk of the car.
The Utah permit is honored in states that have formal reciprocity with Utah and vice versa. On the back of the Utah permit is a phone number that states "For LE only" to call and receive guidance as to honoring the permit.
While I've never had to show my Utah permit, I hope that any local LE takes an intelligent stance on my carrying a CW with it.
I don't concern myself with what police think. I follow the law. Are you really going to center you own self defense around what police might think of your permit if state law says that it is accepted?
Unless you are legally required to inform in the state you are standing in at the time, keep your mouth shut about your gun and your permit, and you likely will not have any problems during a routine traffic stop or other routine contact with police.
Mass resident here, the only way to legally carry in the Republic of Massachusetts is with a Mass permit. Most of New England except VT is like that. I have Mass, Utah, FL, ME, CT. Still cant carry in RI, New
Hampshire, NJ, or NY. Will apply for New Hampshire next. I think the Mass permit is pretty tough for an out or stater to get. The other New England States are Doable, RI requires some proficiency testing.