I ride a 155 and weigh 160. I have spent time riding both 163 and 155. I can ride both equally well but prefer the 155 in most situations. I like the way the 155 carves better when I lay it on it's side and is easier for me to handle. The only time I wish for the 163 is when I am lost in a jungle of tight trees moving real slow, looking for a way out. The 163 will float a little better in that situation. If I have to almost stop going up hill, the 163 will keep moving a little better than the 155. Keep a little speed and they both work equally well. If I weighed closer to 200, I would be riding the 163. In the deep snow, I don't think the tipped rails make much difference.
My riding buddy has a 163 with tipped rails. It is really hard on HiFax. The center of them seem to wear out and leave both ends. My 155 has yet to show any signs of wear. We both ride the same trails and same miles with scratchers down at the same times. He is on his second HiFax and they are almost gone, mine still look new.
D