I have both F4Ss and F3HPs and while I absolutely love my F4S I tend to use the F3's more. I haven't analysed it but quick thought says that my old glass is a lot easier to use on the F3. But I love the spot metering on the F4 and the viewfinder diopter used to be a life saver for me when my cataracts were active.
However if you're going to add AF lenses to your bag, an F4 might prove handier in the long run. Both are unbelievably cheap right now.