I can't believe I sat here and read through this entire thread in one go, but I did none-the-less, so I may as well post now.
I really don't see the 4E rules as being necessarily problematic for the reasons that most people claim they are. A lot of what people like Hypersmurf said earlier in the thread, about not assuming that healing undoes damage, is very much true.
Anyways, there are three main numbers that can be used to determine how damage a character is: current HP (which is restored with Healing Surges), Healing Surges remaining (which is resotred with an Extended Rest), and the current number of failed Death Saving Throws (which is healed with a rest). The interplay of these three is a bit complicated, but because each one is so specific and has a distinct purpose, you can pretty easily construct a set of "narrative rules" to describe damage without ever contradicting them.
First off, HP damage can be any form of damage. You can lose HP by getting hit by a monster's claw, by taking psychic damage, etc. If you lose HP, then it means you have taken an "actual wound", though they are not necessarily all that big or life-threatening. Most likely, most wounds would be minor scratches or bruises, because they can't be life-threatening until they knock you into the negatives. However, gaining HP does not necessarily mean that an actual wound has closed, since HP can be restored through raw grit, willpower, and the occasional Inspiring Word. However, increased HP does mean that you can continue to take additional wounds, so there is a real improvement to the character's physical and/or psychological condition when HP increases. If anything, HP is more mental than it is physical.
Anyways, A Healing Surge represents your capability to be healed, so it works well as an abstraction of the body's physical ability to keep going. It represents the total sum of things like adrenaline, the limits of the immune system, reserves of endorphins, reserves of blood, raw physical fatigue levels, and the like. In a fantastic setting, even more obscure principles of Ki and the like can be folded into this limit. These are resources that can even transform psychological motivation into real physical improvement, but they are finite, and need time, rest, and nutrition in order to be recovered, in other words, an Extended Rest (I can't imagine how important a good, hot meal must be to a guy who has been cut apart with swords and claws all day).
So long as a character doesn't fall beneath 0 HP, and potentially lethal wounds are not a concern, I can't agree that there is any problem at all with "Quantum wounding" if you use simple assumptions like these. Of course, I don't think it is a problem even if lethal wounds do come into it, but I am still getting there.
The issue of "Shrodinger's Wounding" only really begins to peek its head when you get into lethal damage. Fortunately, 4E doesn't have the "bleeding and losing HP until stabilized" rule, so I can actually count raw negative HP damage out of the discussion. Sure, if you get reduced to a certain negative HP value you die, but that can easily be narrated as your luck running out and the blow that finally did knock you that low was in fact a 100% guaranteed fatal blow, with no room for discussion. The only complications appear when you factor in the Death Saving Throw.
The problem with the Death Saving Throw is that if you make the save you don't suffer any lasting penalties, and if you don't make the save you are stuck with a penalty (the hanging failed saving throw) until you make a Short or Extended Rest (where you presumably get the offending wound stitched up or something). There actually is wiggle room for "Quantum Wounding" to appear here, since the question of "is this a lasting, penalizing wound?" is not answered until well after the wound is actually inflicted, which can make narration a bit tricky. Fortunately, I don't think this is an unsolvable problem, but I will admit some difficulty in putting my answer to that problem in words... Something about the saving throw reflecting the character's body's response to the wound, either clotting up and closing the wound or it getting worse, or something like that. Sorry, I can't seem to get it right.
Anyways, there are certainly a few situations that some people have been claiming to be true that clearly are not. A character who has been restored to normal condition from the Dying state by a Warlord's Inspiring Word is not necessarily at "100%". Such a character can not possibly have all of his Healing Surges, and if he was actually at risk of dying from his present injuries (meaning he has two failed death saving throws), then that risk is still present, making it far riskier for him to fall into the Dying condition again before getting those penalties cleared. The simple fact that the character has been roused into consciousness means he is at no more risk of being finished off without any luck to save him (the negative HP limit).
Also, while it may be a risk to touch the conversation regarding Raven Crowking's "sandbox style" even with a ten-foot pole, I suppose I may as well do so anyway.
Based on what I understand of Mr. Crowking's preferred style, there may in fact be a logical disconnect between it and the healing rules as they are written and intended. However, I don't think this disconnect has anything to do with the "Quantum Wounding" principle. Furthermore, the number of assumptions that Mr. Crowking has claimed are behind his definition of "sandbox" means that it really is a fairly specific corner case. Actually, I think there is a certain argument to be made that sandbox vs. episodic is the irrelevant part of the distinction he is making, and that the important part is whether or not the characters are presumed to have any protracted downtime or not (which can occur in either episodic or sandbox games). However, if this kind of realism is necessary or you and you play in a game with no assumptions of protracted downtime, then there may very well be a logical disconnect with the rules. But again, this is only a problem for a limited sub-set of players looking for a particular experience, so I think it is more appropriate to create house rules to make the problem work for you than it is to condemn a system that works very well in most other situations.
My suggestion for a house rule would be to simply slow down the rate of how many Healing Surges are restored for each Extended Rest. That way, characters can still enter battle at full HP, but it means that every so often, depending on how well they fight, they may need to take a break from fighting so they don't get stuck in a hard battle without any healing surges. If you want something more complicated, you can probably concoct something based on making characters give up the potential to regain a Healing Surge in order to make failed Death Saving Throws go away.