I think personally, if you're going be riding a lot of switch you should get them closer to true center, depends where you're going though, if you only hit the park and ski groomed runs I'd say closer to true center, but if you ski in pow time to time, you'd probably want them a little bit back from TC. It really sucks when you have your tips digging into the snow all the time. usually 3-4 cm back from TC works for me, I find that I can turn a lot easier on normal runs outside the park compared to having them true centered (with the exception of skiing switch)