I just came back from SLC (hello any one miss this on my many annoying posts extolling the place?! :-) )
And I had 3 days of FRESH powder, mind you exceptionally light and fluffy, that was between 8" and 2-2.5ft deep depending. This is only the 2nd time in deeper powder for me, last year being the first at JH and I had a lot of problems then, especially above 1 ft or so.
BUT, for whatever reasons, I seem to have fixed the problems and had a blast on relatively TAME terrain in the deep(er) stuff. And no problem steering around up to waist deep in places off the main trails.
My skis & build -- 174cm, K2 mod X (shaped), 199.99 pounds, 6'1".
I found the easiest and best bet to ski in the sutff was to: stay balanced over the ski but SLIGHTLY tips up and LET the ski turn, no forcing of anything, and just turn BOTH skis at once and let them do the work (no wedging or christie). Also I kept my feet about 6-8 (?) inches apart as I normally would on groomed trails.
More aggressive turning could be had with some good pole planting and "hopping" but I didn't get too far down this path...
No problem at all in the stuff, in fact, all I could think of was a) what blast I having, and b) like a drug addict, how I'm totally hooked I'd become on the sensations.
Now if I lived out that way, I'd probably buy a slightly fatter all mountain ski and use that 90% of the time and if I really got into it and hit the "backcountry" stuff, maybe a fat powder skier... MAYBE.
So no problem with side cut I could see but very limited experience... AND you have to give some credit to the UTAH snow which has less water content than ANY snow, I think, in general. So probably less grabby and easier to maneuver about in...