I was in the same situation as you, and I mounted the skis like 2 cm forward of classic. Which was good, but then I started skiing exclusively park... so I wish I had originally just put them center. I was never able to feel any difference anyway, they still ski groomers fine. I would go center, especially if you think you might end up skiing more park down the road.
I have them, and I don't really like them. They are heavy and really don't work how they were intended. Mine when I move them forward, they slide back so you can't mount them where you want. Hope that clears that up.