the myth that waxing your skis makes your bases softer is bullshit. Park skis made in the past few years are so hard, the wax can barely soak in at all. This is why park skis are not as fast as other skis in wax tests. Using a cold weather wax will help because they solidify better, filling the pores with a more solid, longer lasting element.
If you like to slide rails, then slide rails. Your bases will take some abuse, but keep them waxed and flat, fix gauges if you get any, and generally take care of your gear. The average park ski is designed to last for 1 season of tough park abuse. That's just a fact. They will last 2 seasons if you take care of them right.
If you dont wax like an earlier post said, your base will dry out, flake off, and get eaten to shit. Your pores will open up allowing moisture and dirt to get into the ski's base and could lead to moisture soaking into the ski's core. This is no bueno and will destroy your skis.
For more info on waxing, and to buy high quality wax for cheap, go to Purl Racing
and read up a bit on waxing, and what the tiny ice crystals we call snow actually do to a ski base.
-'Kevin, how ya been?'
'Oh, you know, up and down'-(Kevin, the elevator guy at the hotel I work at.)