Perhaps the discussion of Caston's skiing vs. the skiing the more technical skiing that has been posted belongs in a separate thread, but I'll comment here anyway.
First, I love Caston's skiing and videos. I have a lot of respect for his speed, athleticism and especially the tactics (and the fitness to pull it off without blowing up) across all the terrain shown in his clips. I think there is a lot to learn from how he approaches terrain and the speed at which he attempts it at. No way would I categorize his skiing as defensive (never liked or used the terms defensive/offensive to describe skiing anyway). Make no mistake, the dude can ski.
I don’t consider Marcus to be a technical skier or necessarily a model for technique though. There are aspects of his skiing that are rooted in very sound fundamentals and others that are the result of his fitness and athleticism—which I think is what Mike was alluding to above—things like arm/shoulder/hip rotation, leaning-in, generally poor separation unless he feels he needs it to wind up, etc. I would argue however, that for this type of skiing, his fundamentals are among the best out there.
He also shows that it is actually COOL when big-mountain ripper combines freeride world tour-like terrain tactics with a fairly strong technical foundation—that it is possible to make bad-ass technical turns without looking like a clone of another skier.