I used to want an F6 but i have decided the F5 is a better choice.
While the F6 does have some technical advantages over the F5, the price difference is very big, you can get a perfectly good fully working F5 that might have a few scratches and maybe a little dent here and there for 300-400 ( without a lens ), for a used F6 in similar condition you're talking 900+ , and most times over 1000 USD ( without a lens ), in my opinion the certain advantages of the F6 over the F5 are not relevant enough to justify paying double the money, the F5 is already a better camera than i am a photographer, it will take me quite a while to get used to all the custom functions and so on.
One of the main arguments is that the F5 is heavy, i personally like cameras with a bit of heft to them, for example the Minolta Motor Drive 1 when coupled to my Minolta X-700 doubles it's weight from 505g to just over 1Kg, and i much prefer it with the Motor Drive on ( it lso adds a nice grip and a vertical shutter release ), so i'd rather have the F5 with the integrated battery grip than the F6 that i would have to buy a grip for ( about 400 USD more! ).