I have found that my stickers last longer at the tips of the skis. They are protected for the most part in front of your bindings. Behind the bindings more snow gets forced over the top sheets, therefore making it harder to keep stickers on the ski.
Anytime you wipe out or land with your skis crossed it can slice the sticker a bit. Your ski edge can damage the sticker, but I have never had it remove one.
When I first put a sticker on my skis, I always make sure to use a credit card or i.d. to scrape the decal and make sure it is really on there good.
Another trick I use is to take an Exacto Knife and cut at a 45 degree around the border of the sticker. This tapers the edges of the stickers and makes them less prone to catch and rip off. I do this to all the stickers on the tails of my skis and it really works great.
Lol now I am going to go try the heat trick!!!! thanks for the good thread.