To me, I can only look at the actual increase it gives, dismissing the "I take X many more hits!" as just a psychological effect.
Not going to argue, I am sure it is somewhat psychological... but honestly ever since I've actually put IF into my build it's been so much better. Now you assume that each hit I was talking about did some 3 hp each, or something... which is not necessarily the case. You can function with only 1hp left. Many times I walk away from a vicious ganking with nought but a sliver of health left and know that is was the small increase in health from my IF that saved me. Heck, the small increase in IF saves me even when I am wearing my peasant gear a heck of a lot... I guess that on average 2 swings from most weapons would be enough to cut someone down who has only 2 IF, but any IF over that amount is
just enough to limp away from such an encounter, and that can mean a world of difference.
Also I feel that our views might differ because you are a battle player, where you can consistently get 1-shot by cav or ranged, making total health not matter much, or pick your fights such that each scenario is more in your favor, be it 1v1 where you just shit on the poor bastard or something... while I play mostly in siege where willingly jumping into a moshpit is mandatory at times. Sometimes surviving in a moshpit on the flag for even a single second or two longer than you would have with lower IF can be a gamechanger, making IF more useful in my siege-player's eyes.
Also, I will admit I also forgot to mention that along with the 4 IF increase I also had a 3 strength increase... my bad. In my opinion if they removed the health bonus from stacking strength, and made IF the only way to increase your max health (and changing the amount of health it gives) then IF would be as useful as athletics or PS. The problem is that each point in strength gives you 1 hp, which is a 2.63% increase per point over the base health (38 hp, according to the character planners). Meanwhile, each point in agility "makes you move a bit faster" which I
think is a 0.5% running speed increase, or something like that. Granted now that agility also provides wpf, it is more balanced, but a single point in strength should not give such a large increase, while each point in IF should grant more.
I don't know dude I played with 0 IF in NA_1 a lot recently topping the scoreboard pretty EZ when I tried. However for strat 1 IF really gets you screwed with the ranged metagame and having no armor at all.
I can do quite well in battle with no IF, as well. Especially as my shielder alt (who shuns IF in favor of riding), and you are a shielder, no? Having that shield in place of IF makes a whole lot of difference... IF and footwork is a non-shielders' only defense against ranged. As I said above, IF is more useful for us (non-shielder) siege guys, I think.