This is an excellent question and thread, Jeff. I had the same question in my mind when considering a non-resident MA CCW permit.
There's a pretty interesting thread on USACarry.com that might give you additional insight:
Difficulty in obtaining Non Resident Carry Permit (Class A) in Mass?
In the end, "personal protection and safety" was the only justification I could come up with, which I suspect won't cut the mustard, so I saved myself $100/year and gave up on the idea.
- Dave