So, does anyone take this perk or is it redundant?
The description says "only if the damage does not kill you", so it won't protect you from one-shot deaths.
I never used it, but I think the idea is neat. I try to never let my health go that low in the first place, though. The problem is that you can't take it until your Restoration reaches level 90 and by then you most likely don't need it anymore.
I've used it on a couple of characters and it, in all fairness, did save me a few times. But, looking at the invested time and resources in getting that perk, compared to how useful it was, and I have to conclude that it isn't worth going for. A potion of Vigorous Healing(restore 100 health, I think) or three is much better to carry. Less hassle too, not having to wait until you're left with 10% of your health. And easier to obtain, is not limited to once every 24 hours and the major investment in Restoration necessary to get the perk.
I take it often when I play characters who never use potions. I have found it to be invaluable for those characters.
I've never used it, never had a reason to. I would think if you have perks to burn then maybe it wouldn't hurt. But as said above, ther perks are better spent elsewhere and a potion would work just as well.
I consider it a 'nice-to-have'. Restoration eventually gets there, but you probably won't experience a significant change once the perk is active. It did save a couple of my PCs a few times so I think you should take it.