Apparently ~80% of the people do argue with this, and assuming you followed the SCOTUS news recently you see just where the distortion of that 5th amendment clause has gotten us. My take on the constitution (I don't know who to attribute the quote to) - 'It isn't a perfect document - it's just better than what we have now.'
*laugh* You want someone else to defend for a while. I don't mind lifeboat scenarios, but don't see focusing on the obscure minutea as opposed to worrying about takings of the style you propose which happen in everyday life. If you are serious, focusing on extreme scenarios only makes sense if you are attempting some kind of slippery slope approach.
I've been starting to think you're just playing devil's advocate anyway. Oh well. Regardless whether you're sincerely a full blown statist, Adam's original 3 scenarios from post #4 (http://solohq.com/Forum/PollDiscussions/0100.shtml#4) are actually interesting to think about.
1- building a defensive perimeter in anticipation of war
I disagree with Adam on that one. If you want to build a wall, make me an offer to buy or rent my land; convince me of the importance of the situation I'll probably deal with you at a modest price. If I stick to keeping my property, the solution isn't stealing it. It's really pretty simple - go to the neighbor behind me and build me outside the wall.
2- razing land which will eminently be conquered by an enemy (I'm assuming the 'igloo' reference was the same as this too)
I'm not one to throw around the term 'hostage' the way some people do when they want to justify bombing whole cities by saying everyone inside is a hostage. However, this circumstance does fit the hostage scenario, one where risking harm to someone in their or others' defense is acceptable only because at least that same harm will occur anyway. If no action is taken, I'll be killed and my home destroyed when the invader strikes my property.
Go ahead and try to get me off the property (and bulldoze that shoddy barn the enemy could somehow strategically use). Keep in mind the good point you made about hostage scenarios before though, concerning Bidinotto and a machine gun. If people with guns pointed at me are coming onto my property, I'm justified in shooting them - even if they think they are rescuers. Better explain the situation really well.
3- property being used or previously used in crime
If I'm currently using property in crime, that's a trivial scenario; I lose rights to the property. Property used in crime by someone else that I now unwittingly have is a bit more interesting.
If you steal a TV, pawn it, and I buy it to take home, I don't have legitimate claim to that TV since you never had legitimate right to sell it. If it's found that I have stolen property, it doesn't make me responsible for your original crime - but I have to relinquish the stolen goods. My claim for my loss of the TV is not with the victim, but with you, the thief who defrauded the pawn shop and myself.
The same principle applies to the other crime cases. Just as I can claim no meaningful property rights to a knife I used to stab someone or a torture room I locked them in, those would not be mine to legitimately transfer either. It's somewhat morbid, but a murdered corpse qualifies as stolen property as well.