Just to clarify a few things.
First off: my coach never implied that it is NECESSARY to change the stance angles (as changing width is not even an option).
He just suggested that, since I never tried nothing but a symmetrical stance, for a more "freeride" approach I might try something a bit more directional, but still duck.
In fact, since I am still basically a noob, I find that leaning back, on a true twin and in rather deep pow (2"plus), is not very easy: I tend to lose my balance a bit either left or right which often cause me to fall.
I think that something like a 18/-6 stance might help me keep my balance as I open my torso towards the fall line a bit more than usual in pow.
Finally, I am more than aware that I am a victim of the gear acquisition syndrome, and at this point my technique is holding me back much more than my equipment.
But my long time goal is one (or more) trip to Canada and/or Japan, so at some point I will want a real pow board.
And seeing the chance of a good deal on a powder snake is just a big temptation: if is still available (and maybe a bit cheaper still) I might treat me to one for my birthday.
I hope I made myself clear enough, but as you can imagine English is not my mother tongue.
Thanks everyone for the replies.