it's different with lines though.  other skis, no problem centermounting, i did it with my old teneighties that were mounted on the ass end of the ski and they were so much better.  but with the lines, i'd say don't do it, cuz the way they make them so damn light is that there's like no thickness to them at all anywhere except the mounting area.  look at your 1260s side on and see how it gets so much thicker in the mounting area?  i wouldn't be comfortable drilling into anywhere else.  besides, they're so light that they're not going to feel any lighter mounted at center, and they're pretty balanced mounted where they are anyways.  if yours still have bindings on them, hold them up with your finger and see where they balance.  for me, with bindings, the balance point is like 1 cm ahead of the rec mounting line, so they're pretty balanced already.
so there's my long-winded reply, but i'd say don't do it.
my level of radness... it just can't... be quantified.