The H.A.W.G. has been my everyday carry pack since I got in back in 2003.
It has been my favorite pack to date.
But recently, I wanted the option of being able to carry a larger load - so I purchased the B.F.M. 500 which seems to be awesome so far (only had it for a couple days now).
I plan on using the B.F.M. for camping, traveling and airsoft 24hr mil-sim games.
The H.A.W.G. I tend to pack with everyday items like a 15in Powerbook laptop, books, power-cords, extra sweater, etc.
I am still playing around with what the B.F.M. can carry, but it seems like it can take a lot of different stuff - much more than the H.A.W.G (18L vs. 50L of gear)