Unless you have a gross chip lead like 6-1 I am not inclided to "push w/ anything." This is assuming the blinds are not outrageous and you are of equal or greater skill than your opponent.

The chip lead lets you poke and prod preflop with some raises and re-raises. You can set some better traps that way. I prefer to play post-flop in heads up situations so you can see if you pair up, bluff etc...

When you get up to 8-1 or more than you can just push AI blind and take a shot or two and ending the thing with any 2 cards.

The risk of doubling someone up when you are only at 4-1 or less is a problem for me. Say you have 20K v. 5K it only takes 2 double ups on the part of your opponent and the tables are turned. On the other hand, if you have a relatively weak opponent you can pound them into submision with that type of chip lead.

In any case, the cards have far more to do with the outcome than any "moves" you make. For instance, I lost AA v. A2 in heads up confrontation, everything went in pre-flop. So, this might be an argument for puhing with any 2.