So to revisit this. While riding today I was thinking about this whole argument and what I actually do and how much difference it makes. What I noticed is that even though my base is flat visually, I am definitely pressuring one edge or the other at all times. Granted, it is very light pressure but it is there. I deliberately went totally flat like I would on a box and even though I was stacked and aligned, the board definitely picked up wobble from the uneven snow on the long flat cat track that is the run out for Heather Canyon at Mt. Hood Meadows. Every little bump, dip and rut affected the board`s trajectory in some fashion. I was able to always make tiny corrections to keep it going flat and straight but it was a total concentration kind of task.
When riding as I normally do with just a bit of edge pressure (not tilt) The board handled so much better and the ride was just easier. So, how did this affect board performance? Well, the snow was firm hardpack that was just softening up from the afternoon sun and was not noticeably sticky. My glide up a short uphill stretch was no different whether I was holding a slight bit of stabilizing edge presser or letting it go totally flat. Maintaining a carve with the edge actually lifted, did mean that I did not coast to the top however.
Later, I tried this in the refrozen hardpack and noticed no difference between flat based, slight edge pressure or carving. In each case, the glide was the same as far as I could measure. Now of course I wax and it does make a difference in our snow.
So, for me, I personally in my riding, am going to continue to ride "flat based: while deliberately hold just a tad of edge pressure. Any loss of glide performance is a small price to pay for the extra margin of control I feel. Because I firmly believe this method is safer than trying to maintain a true 100% flat base, I am going to recommend using light edge pressure; especially with beginners and intermediates. Others can do it any way they like and if they are comfortable being truly flat based, that`s their call. I am going with flat but pressured.
this is basically me entire argument. there is really no reason to sacrifice the control you have for an almost immeasurable amount of additional glide or speed..and generally, you need to put pressure one way or the other to correct yourself if you are truly flat regardless.