Dude, i'm not sure how different the magne is from the banana, but i just got a roxy envi with mtx and was lucky enough to have pow in spring, i just floated over it, and when it got icy and slushy the next day it really helped my ride. i felt the difference in the edge control. you are alot more experienced than me, so you will probably totally be able to fully benefit from it. a friend of mine has been boarding for ten years and swears by his lib tech. peace.
I'm guessing that's a typo cause MTX is simply magnetraction, BTX would be the Banana/reverse camber which would be the only helpful part in floating on powder, MTX is just simply a wavy edge design. BTX also includes magnetraction though.