IF reduces armor weight penalties against wpf. Each point takes away 2kg. If you're wearing anything heavier than Lamellar Vest with mail accessories then you're better off with the IF. 6IF (12kg reduction against weight penalty and 12 hp) > 1 wpf and 1 athl. Well, on paper at least, sidestrafe glance and "S"key best key are going to win 90% of the time. Take the 1 athl, wear the plate, and fuck the wpf.
Don't quote me but I think the formula is: 6 base + str/3 + if(2) = Max armor weight before penalty.
