Lots to consider here. I play mainly STTs and, aside from the times I am against a familiar opponent whom I have a good read on, I am generally unwilling to stack-off early in the tourney with AK, toward the later stages, definately willing to shove/call a shove with AK.
Aside from the typical tight early/loose late strategy that is common, I simply feel that I have an advantage over much of the table in these STTs and am unwilling to be calling a shove early where I am likely to be flipping. I feel I'll find better spots later-on. as the table gets shorter and everyone's 'M' declines, then you need to be willing to take those opportunities that, maybe early-on, you'd shy away from.