Replying to Where to mount bindings on armada thall 2011-12 model

I just picked up a pair of t-hall 2012's earlier in the summer. I'm finally getting them mounted with a pair of marker griffons (yes i know.. but they were free.) I was thinking of getting the skis center mounted for better performance in the park which is pretty much all i will be doing. On the ski it says the recommended mounting point is -2.5, but i feel like this will make me more unstable on rails. Also since the skis aren't symmetrical i feel like there will also be performance issues. Please help me out, first hand experiences are helpful :)