I'm in the "screw it down because they're supposed to be" club.
What I would love to find though are 12-24 Robertson screws (trust me, I've looked and unless I want to buy 1000 of them, they aren't around) as they'd be so much easier to remove and install than the flat head screws.
That said, I rarely ever remove the floorboards, so it's one of those things I live with.
(Oh, I also bent the washers so they are more accurate per the JS than the as-purchased concave ones...but again...probably a little bit over the top...)