Steve:
I agree with your logic! We have to get away from 'bedrooms' as there are other areas that require AFCI.
IMHO, if anyone is concerned (my word choice) of AF, there is no reson that the whole house could be AFCI, although it is NOT presently mandated by code. AFCI is 'new' here in NJ, as of 10/06/209 when '08 was adopted without an AFCI amendment, as in prior code cycles. That said, there is a project that had AFCI in the BR's only, by spec, and I'm not aware of any issues there to date.
We have a lot of 'growing pains' to go thru here in NJ with AFCI's, and as I have said to Harold, I'm not missing being an EC!
