basically, the quality on the burton insulator is lower than similar priced mountaineering company ones (as mentioned already patagonia etc). The Burton has two things in it's favour though:
1) it's Burton, so mass produced and it's easier to find last season's stock on sale
2) it has pit zips where the others don't
This, which I personally find mandatory. I had last years AK Insulator, which I would only use when it was -10c or more. Still I find it was a bit over kill and bulky. I bought this years Ak helium insulator which is a lot more low profile, and still very warm. I havent hit -10 yet, but im confident with a marino base, the lower profile AK insulator and 3L goretex shell it will be just what I need.
In either case I find the pit zips a must. If you over heat in one of those things you are toast....literally.