It was meant to be two questions with three phrasings apiece.
Anyway, I'd advise against having it fill the Toughness boxes. That really defeats the purpose of it giving Toughness.
By the way, how does this work if you already have physical Powers?
Is it unprecedented to have some powers specifically not work with each other? I can't think of any off the top of my head, but due to the narrative of this power(Rock lee only having physical power, taijitsu I believe, in the show), it would make sense if the person couldn't have any other physical powers, and was limited in the powers they could take at all.
If it fills the toughness boxes, it's basically just gives armor, with some form of catch. Which is a waste of refresh, but since you aren't paying it's kinda moot. I think it works in terms of flavor, he becomes tougher as well as stronger and faster, but I don't feel the mechanics aren't quite lining up right. I do think it's getting closer to the right feel though.
I just noticed, that it's take up to in consequence, not take that specific consequence. That makes it alot harsher than I realized. Not sure if that's good or bad though.
Some food for thought, with the current implementation, once they break 6 gates, they add 2 to their defense roll, and get 2 armor. For someone of the same skill for attacking as this characters athletics and no super natural bonus they will hit only 1 in 4 attacks, and less than 1 in 20 will they hit well enough to inflict stress pre-weapon. Since all they need is a stress of 1 to either force an extreme or take him out though, assuming at least a weapon 1, they will achieve that close to 1 in every 7 attacks.
At the extreme level gate 8, assuming attacks are coming in with weapon 2 and at the same skill rank, it's 1 in 20 to take out the power user, 1 in 140ish to deal damage without a weapon rating, and 1 in 7 to to hit with no stress, pre weapon.
At gate 2 and 4, it's a little less likely than a 1 in 2 and a little more likely than a 1 in 4, to hit with no stress, pre weapon respectively.
Looking at that I'm thinking gate 4 is a little light, and doesn't scale with the others, since a moderate sticks around for a session +, Maybe kick in inhuman toughness at that level with the current implementation?
I still think stress caused equals stress taken is the model to use though. It has a nice karmic feel to it, fits the whole Eastern obsession with balance pretty well.