I think every ski should be mounted where the manufacturer recomends.  Some people want them 'center mounted' for jib which wastes the sidecut and turning raduis is well, greatly reduced.  Others mount them back for powder......which once again basically wastes the design of the ski.  I always say stick with manuf. recomendations because that ski is built to be mounted at that point...not back, not forward but at the sweet spot.
If you want better flotation in powder then perhaps you should look at a powder ski.  Better spin ski???  Look at a good jib ski like the PE, 1080, whatever.  Mix?  Something like the Pocket Rocket.
All of these skis have rec. points.  I think mounting in a different spot fux the ski's performance up.
I've tried skis mounted in different spot and I think it ruins em.