Opinions on what's going on:
Could someone PLEASE explain to me why my floor press is at least 50 pounds (closer to 400#) more then my unequipped bench press (350# or so) with the same grip? What weakness does this indicate & how can it be remedied?
It seems to me you need more work off your chest and leg drive. Body structure has a lot to do with it as well. If you're light with longer arms, then it's closer to a half press, but if you're heavy it might be like a full press. It could be form related as well.
well it could be that you dont have the lat pec and upper back strength to match your shoulder and tricep strength. with the raw bench you have to use your lats and pecs to get it started then the triceps and shoulders finish it. Or the lats and shoulders to get it started and pecs and tri's to finish. either way you need more lats and upper back You dont get lat involvement with the floor press.