The Helix is a ill ski. i spent most of the 09 season an a set of these. they were a much better in the slack/back country then on groomers but i wouldn't let that stop you. if you buy'em you wont be disappointed. enjoy the season.
o btw, do you have or know anyone who has a set of marker barons for sale? if so let me know i would like to get a AT set up.
and just my two cents on the bindings if you're going to be skiing primarily backcountry on your AT setup I would probably recommend the Fritschi's due the weight and the fact that you don't have to take your foot out of the binding to switch modes. The markers are seriously heavy, Bomber bindings but Heavy, they seem to be better for more inbounds with some occasional touring.