This is not exactly true. You are only "washing speed off" if you are skidding. Being on edge does not equate to skidding and in many snow conditions, carving on edge is actually faster than riding with the base flat......
+1, I can confirm this theory after riding velcro on Wednesday. Got to the bottom of Cypress and it was sticky snow, did little carves at the bottom and I could barely feel the glue. Put the base down and it was like the drag chutes were deployed!!!
For what it's worth, my board builder setup my edges at 0.5 deg base, 2 deg side bevel. He does this to all his boards including race, alpine and BX boards. Lonerider said it engaged to early for his liking, I personally love the way it grabs HARD. It's very dramatic and once used to it there's no second guessing.