Talked to one of the Moment reps at a movie premiere in Lake Tahoe last night, and I asked him about the square tips and tails. According to him, it makes absolutely no difference in the skis' performance. The only reason the skis have the squared tips is so they are easily recognizable. It's purely cosmetic.
That said, I'm not so sure about the durability of Moments. A coworker of mine did a lot of work and binding mounting for their team riders the last two years, and he said virtually every pair of skis he worked on either snapped or had the bindings pull out of the core. Dunno if this is still an issue, because there were still a lot of prototype skis being tested the past two years, but I'd still be cautious.