(to start off I'll say I ran a search but all I turned up was that CH3/CH4 is a royal bitch to scrape, but didn't find too much further detail on it's benefits)
Even with relatively thick layers (i.e. not-quiet-complete scraping and sub-par brushing) of my warm weather moly flouro wax (and even my warm weather hydrocarbon) wears off under the bindings after just 4000 vertical feet. On racing days, even when I have an overlay, this isn't optimal. But worse, on freeskiing days when trying to have fun I'd rather not have to carry around my F4 paste wax or buy something else to lug around the hill just to maintain performance.
So, the question is: is is worth the extra time/hassle to put a super-hard wax under the bindings to make that area's wax-cover last longer???
Also, "warm" snow isn't necessarily soft. In fact, loose granular can be hard as rock (on a microscopic scale)... therefore why have a softer wax? Also, when you have pine needles, sticks, twigs, mud, and other crap, won't a harder wax resist that better?
(btw, I know that SWIX school teaches this in the "racing" section, but I wasn't sure what people actually do).