Grats to all for this huge Kickstarter success. Sadly I couldn't watch the stream at the end because of work, but it must have been quite the celebration.
My thoughts on the discussions here, for what they're worth:
Health and Stamina: The system itself doesn't matter to me. Using any system at all, fights can be made to be challenging, which I'd like them to be. People could rest spam before and this system addresses that. The thing about designers putting in restrictions in their mechanics is rarely to stop players from having fun playing the way they want to. It is because they understand human psychology. If there is a tedious and unfun, but optimal way of playing a game, people will either tend towards that way or feel like they're punishing themselves and making their character weaker every time they deviate from it. "Forcing" players into a more engaging playstyle isn't patronizing, it is a designers job. People who truly enjoy unfun stuff should still be able to do it, but it shouldn't be encouraged through rewards for the above reasons. It can be made viable, but never encouraged.
Anyways, as long as I will spend evenings working out tactics to beat a difficult encounter, the numbers that the PC is crunching in the background don't matter to me in the slightest. And if anyone here seriously believes that this game will have health or stamina regenerating in combat to the point where it's impossible to die, then what are you even doing here backing the project?
Quest XP vs. Kill XP: I'll just lay my own bias on the table up front: I like Baldur's Gate 2. It is the best RPG and indeed best game ever made for any platform and surpassed by none. Its mechanics are, to me, perfect for their purpose, namely allowing for, and being conductive to, a fun RPG experience in the style of PnP roleplaying games. Making an IE game should mean to take your inspiration in large part from Baldur's Gate 2. I'm not stubborn and will require the devs to make everything like BG2 without any change, I can accept reasonable and well-founded changes and I accept the health stamina thing because it sounds sensible to me. But there have to be good reasons for you to say that you can "improve" on BG2 mechanics.
I have played the IE games a lot and not always in the intended way. I have honestly never felt in a position where I was too weak or unbeatably strong. What issues is this new system meant to solve? If there was a problem in BG2 with people grinding I could see the need, but there simply wasn't, because monsters didn't respawn. Why implement this whole new system for something that BG2 already had the solution for 12 years ago? Kill-XP couldn't be abused because there was no way to grind, and if there was (travelling back and forth to get random encounters) those would be so hugely inefficient compared to continuing with the storyline that the designers successfully made it a non-issue. On the other hand: Kill-XP does have advantages. Small incremental rewards are just hugely more efficient at motivating players to go on, they give the feeling of continued progress. Let's be honest, we roleplayers like to see the numbers go up.
As for the problem of metagaming multiple paths: As has been said many times in the thread, for the AIs that are aligned to some quest, just set one little flag in there that checks if another way of solving the quest has already been taken. If so, they give nothing except loot (which, by the way, would still exist in the quest-XP system and therefore would still give an incentive to kill everyone anyways, so I don't really understand that point unless you want to do away with loot for killing as well and go to a "quest-loot only" system). Maybe you get a tag like "Slaughterer" for the unnecessary violence that will get you respected in some parts, frowned upon in others. If you kill the lawful quest givers, that's even easier to punish. Give the tag "Murderer" and have most shops closed to the player.
I think there is no reason that I can see to do away with kill-XP in a well-designed game, and there are some reasons to keep it.
That's my view of this stuff, I am always open to be convinced though.