And separating HP and physical damage is a good trick. I like to think of the first solid hit as being the one that bloodies the target. Everyone has their own HP. The wizard is deflecting blows with magic, the rogue is twisting and rolling with hits, etc. I'm surprised you suggested this. Most simulationists I know hate the idea of abstracting HPs.
While I'm a simulationist, I only wear the viking helmet occasionally.

I think the abstraction that is hit points can be a really good one at mechanically representing the things I mention. As long as actual physical damage is removed from the mix, then you can run the game more efficiently in a simulationist manner without having to go to the next degree of hit locations and large and many tables of data.
Well poison is a bad example.
Or at least I think my example of it was a poor one at articulating my dissatisfaction with this element of 4e play. As I mentioned to NeonChameleon, for me it is as much about the process as the result. I want the two to mesh together in a satisfying (to me as a "simulationist") way.
But why would a spell be physically exhausting while a physical maneuver isn't? I think our main difference here is that you don't see martial characters as fantastical and impossible, and I do.
Magic is more exhausting than regular combat was more what I was getting at here as a way of balancing a 3e/Pathfinder style wizard to the fighter. I prefer this method of balance than the one used in 4e. Again, I'm not that conservative in terms of martial characters but I have a lower threshold than your good self on this issue.
I again agree. This is an example of sacrificing detail and realism to achieve simplicity. You can explain away many things, perhaps the wizard is augmenting his strength checks with some magic, and your dumb fighter would probably learn a few tricks from experience. At some point you are going to great stretches to explain why your level 15 barbarian who has never seen a lock before can pick it with ease, but it's a sacrifice I make

.
I agree here, I would just prefer 4e to allow a little more complexity on this one.
I think this is the one point where we disagree most. If you were to bind fighters by the laws of reality and disallow them any magical explanation for their abilities, they wouldn't last. There's no sensible reason a high level fighter should be able to soak 150ft of falling damage.
In my dual hp model such damage would be directly applied to physical damage, although you could still "spend" hit points in trying to grab hold of something on the way down to lessen the impact (something that the high level adventurer would be better at than a lower level one).
If a first level commoner stabs a sword through the fighter's neck in his sleep, he gets up, bludgeons the commoner to death, and goes back to sleep to get his HPs back. A 30th level fighter, (or 20th, in 3e, etc...) can survive 8 doses of poison that would kill a level 1, even if he hasn't built resistance to that particular poison. That's impossible.
Exactly. Which is why damage from a knife in the neck while sleeping should go straight to the physical damage part bypassing being able to take it as hit point damage if one was awake and readied. As I said, separating physical damage from hit points provides a natural simulationist clarity to these awkward 3e/4e corner-cases.
It could only happen in a fantasy world. It could only happen if something outside of phsyics, chem, and biology were on the fighter's side. And without these things, the fighter can't compete with the wizard, so these things are necessary to have the game.
You see I don't think an adventurer of any ilk should be able to defy the gameworld physics and logic without a very good reason (such as magic or divine intervention or upon the most extreme of cases: dumb luck).
Sorry, the remark about the textbook made me thing you were struggling with the math.
That's cool and no need to apologize at all (even though I have a Mathematic's degree and have tutored high school and university students in mathematics for over seventeen years in my spare time

).
I'm not sure what a realistic market for magic items would look like.
My own preference is for a much flatter structure where an exquisitely constructed piece of full plate armour is the most expensive thing that you can actually purchase. There is generally not enough coin around to pay for highly magical items, so such items are either traded for something else (land, title, honour, other magical items or services) or else given away or possibly sold on the cheap in a black market.
But if you're saying that the wealth a high level PC carries makes most economies look trivial, and that such a world wouldn't function, then you have a point.
It would function but in a bizarre way that I have little comprehension of and so would struggle to roleplay with.
It's very eerily reminiscent of the way we construct math models at school. We can add more parameters to a model to make it behave how we would expect in some situations, but it doesn't make it better. We are just overfitting the model to the data.
What you class as overfitting and what I class as overfitting may differ, but I truly grock your point here.
So I'm on the simplicity side of the argument. And not because it's my own personal play-style. I think most changes intended to make a game more simulationist don't do so in a measurable way. They only increase bookkeeping.
Where as for me, I like the dual hit point idea, a dual, Double DC core mechanic and a handful of other ideas so as the process elegantly matches the situation with satisfying nods to abstracting things that should be naturally abstracted and representing things that should be represented. Where we draw the line between the two may differ a little though.
Best Regards
Herremann the Wise
PS: I tried to XP you for the extended and well considered discussion but alas I must be more liberal with my XP giving first. If someone would be so kind as to pass some XP cheer to eriktheguy, I think it is well deserved.