I currently own both. They are quite different animals... The HP2 is an awesome off road machine. With some work and dollars it could well be the ultimate world touring machine. The F8 is very good, but under-sprung and under-powered compared to the HP2. It is a nice bike (the F8), but it is not in the same zip code as the HP2.
The HP2 feels much lighter than the F8, and it can be pointed at just about anything you would contemplate with a dirt bike. The F8 is very good, but not as confidence inspiring by a long margin. Just by seat of the pants impression, forget the numbers, the HP2 is an amazing motorcycle.
my favorite bike - R1200GS