"...the likely hood of a line-to-neutral fault in branch-circuit
wiring causing a fire is very rare"


A AFCI protects against more than "line-to-neutral" faults. Did you read the
WHOLE article as I suggested:

"The performance tests comparing AFCI/GFI with a standard circuit breaker
demonstrated that AFCI/GFCI circuit breakers will save lives under the
conditions identified by the manufacturers, including from loose terminals
or connections. The comparison test was simple; there were two outlet boxes
each containing a duplex receptacle with loose terminals. A 1,500W load was
applied to each, and after an hour or so, the receptacles melted and the
AFCI/GFI circuit breaker opened within three to eight half-cycles, whereas
the standard circuit breaker did not trip."

Ahh... loose terminals or connections=HEAT=FIRE!

Read the whole article, please!

Jake