At what point (HU) do you quit playing flops and focus on AI only?

[Misfire]

[ QUOTE ]
SNG. You've gotten to heads-up against an opponent. The blinds just went up to X. At X, do you never call PF, do you only go AI or fold? What is X? Can there always be some play? Are there some hands you might just call with or just min-raise with? Does your opponent matter?

[/ QUOTE ]

I've read a couple (possibly contradictory?) things. Not sure if any of this is right, and I'm certainly not an SNG pro, so read this as a skeptic and rip it up as you see fit. If this is worthless crap, please say so and why.

The first thing I've heard is that you should become more agressive as the difference between the two chipstacks grows, and more passive as they move closer to equal.

The other thing I've heard is that the best player in the world can only expect to win about 55% of the time starting with equal stacks against a monkey who pushes every hand.