I'm a tad late to the party, but after giving it some thought I wanted to put in my two cents on the proposed stamina/health system. In summation, I like the *concept* of a mixed system, but I'm not crazy about the discussed implementation. To explain why, I will use as an example my favorite implementation of a combined health and stamina system; no, not Betrayal at Krondor, not Darklands, but Quest for Glory.
I consider QFG something of a paragon of great game design, and while it's obviously not completely analogous to a pure RPG such as PE, I think the basic lessons of how the system was implemented apply. My first relevant issue w/the PE system: Stamina and Health are too close to being the same thing. Obviously I don't know the exact specifics of the proposed system, but it sounds as if Stamina is just a slightly easier to regenerate buffer on health. Ok, fine, but why? In QFG, Stamina was a universal resource. Basically everything you did used some stamina (including getting hit), and that worked well. Health would only be lost from being hit (or doing things that would obviously damage health like falling), or if you had no stamina, anything you did would damage health. If you're going to have a dual-system, have an actual reason and separate purpose for both stats, not just that it's a solution to a meta-design problem.
And speaking of the primary issue here: rest scumming... QFG provides a nice guide to how to prevent it: simply don't allow it. I'm sure most people here are familiar with the system, but in QFG it went like this -- a short rest could be taken to restore a small amount of stamina and no health. You could rest for a while, but eventually you'd stop being tired, and couldn't rest. How hard would a system like that be to implement in an RPG? Not hard at all. You could only restore your health with a full night's rest, which you could only do after you became tired, not at any time. I mean, the IE games already had a fatigue system built in. If preventing rest-scumming is the primary motivation behind this system, then it should be reconsidered.
Finally, the question of the rate at which you can restore health/stamina. As mentioned, there was a fair bit of attrition in QFG, though nothing unmanagable. Health potions were difficult to come by (except in 2, where you could buy like a billion) and were often prohibitively expensive. All this necessitated was intelligent use of resources, not resting all the damn time. Why? Because the rest of the game was intelligently designed to make the attrition both manageable and challenging. This is what Josh Sawyer and co should be aiming for; intelligent encounter design, well dispersed resources, and a system that encourages good use of those resources.
Again, I'm not set against a stamina/health system, but there should be a solid design reason for having stamina as an additional resource, not just preventing excessive resting. Maybe they do have that and just haven't expanded on it yet, but just having the system for the sake of having the system and being different is lazy design. If you want to make health harder to restore, that's fine -- but having a second health stat with no other explained in-game purpose (yes, that's basically what it sounds like) is just redundant.