I had mentioned the Kasparov comparison to show that you can't make an extension from results of benevolent 6-piece tablebases to those of benevolent 32-piece tablebases because of the fact that a low-level player able to hold the draw in the endgame situation will also usually be able to hold it against Kasparov.  In an actual game, just as he would lose to Kasparov immediately, there would still occur many positions of sufficient complexity against a benevolent 32-piece tablebase so as to require deep, precise play--my belief is that, in general, these positions would occur noticeably more, not noticeably less, than in games with which we're more familiar.  Unless, of course...

Unless we allow for the two players to work together to produce a draw by third repetition.  I knew that the discussion would eventually come to this, and I didn't address it earlier because this is something different altogether--this is a situation in which a technicality in the rules is what fixes the game result, a technicality that in many situations, including the example you gave, really has nothing to do with the actual game of chess (though there are obviously situations that we see all the time in which it is best for BOTH sides to repeat).  You might just as well have said, 1.Nf3 Nf6 2.Ng1 Ng8 3.Nf3 Nf6 etc.  I think the discussion is really only worthwhile if we make the provision that the position must be "played out" to where technicalities such as intentional third repetition aren't allowed unless it happens to be the one move that holds the draw.  You might think this sounds silly, but we are talking about something very, very different if we allow for intentional third-repetition.

I think that referring to your article is kind of changing the subject somewhat, but I will comment that as soon as I hit the link, I remembered the article, remembering that I was glad even at the time you wrote it and that it came as a necessary rebuttal to the ridiculous claims made by the Crafty analysis group--my first comment after reading that original article was that all they'd done is found which grandmasters play most similarly to a non-tactical third-tier chess engine.  In reality, I think that such a method might be possible with a much stronger engine (such as Rybka or even Shredder or Fritz or, better yet, all three combined) if retrograde analysis of the game is first performed and stored before going back through the game.  However, this by itself doesn't overcome the problem that you note having to do with psychological elements, such as playing moves that you happen to know will cause difficulty for that particular player, but might not cause difficulty for some other player.  Thus, in addition, in the retrograde analysis, one would have to make some sort of lower limit for recording the evaluation difference between "best" move and the text move--perhaps at least 0.25 pawns, which is often used as a criterion for difference between best and second-best moves to determine the probability that someone cheated by using a particular computer program in a game.  This, or perhaps double the amount, would overcome most (but not all) psychological problems.  Of course, there still remains the problem that some players are far more tactical players than others, and so Fischer and Kasparov would still probably be graded down just because of their styles.