Both pickups are designed for neck position use IMO, though there is a specific bridge position PAF Pro model. I find the PAF Pro to be a bit more vintage sounding, cleans up very well, and has a very cool "tubular" round sound under gain. Listen to Satriani's "House Full of Bullets" or "The Mighty Turtle Head" and that's the PAF Pro without a doubt. The low E string sounds very cool, fat and punchy but still has a somewhat hollow character.
The Air Norton comes across being more modern to me, also cleans up nicely, but can take on a few different voices depending on where you're at on the neck and how you're attacking the strings. The reference I always use for this pickup is Petrucci's solo on the Dream Theater song "Scarred". When he's shredding it sounds round and vocal, then when he digs in and waggles that wide vibrato it sounds aggressive and pissy.
Both are very cool pickups IMO, and are my two favorite DiMarzios and two of my favorite neck pickups ever (along with the PGn and A2P).
EDIT: FWIW, what body wood are we talking here? I had the PAF Pro in an all mahogany Schecter and it did get a bit muddy on the low end, while the Air Norton did well in a mahogany guitar. The PP definitely likes woods more along the lines of basswood, etc.