Roller skis are really intended for race and nordic training.They're pretty expensive, really heavy, and pretty stupid if you're trying to use them to help you with freestyle.Rollerblading is pretty cool if you're really good at it and have lots of friends who do it so you don't get your ass kicked by skateboarders. Honestly though, I think skateboarding is super helpful for skiing. It keeps you in the right mentality, and it makes you really thankful that skis are attached. That, and falling all the time helps if you like skiing rails a lot.