if your skiing not for money or glory and touching the edges every few days, seems to me that ending with something around 400 is totally adaquate.
Round here, seems that the edges hit stuff often enough that the stone often has to be used before the iron, so a few light pressure passes with a coarse stone and some alcahol before hot wax works well for me.
So my reasoning is that constant battle damage screws up the benefit/cost relationship of using finer stones. Plus, the bevel seems to control how much a ski bites more than going to a rediculously fine stone.
There seems to be a lot of debate over the 'hanging edge' and how to remove it and/or if it is even critical past a certain size.