save yourself some money and go to a motorcycle shop. You can buy spine protection armor for less than half that price. one of my friends has a brother that races motorcycles and he just uses his bro's "motorcycle" spine protector, which does exactly the same thing. samething goes for helmets. you can probably get non "snowboarding" specific helmets for a good deal less (e.g. full face downhill mtn. biking helmets like posted in that one other thread).
every company out there is looking to cash in on the snowboarding crazy/fad (since 95% of snowboarders are a fad...). they take some generic piece of protection equipment and jack up the price saying it's for snowboarding.
Besides, vertebrae (especially those in the lumbar region) are pretty tough to fracture. I landed pretty hard on my back one time that i felt electric shock like tingling in my toes and finger tips every morning for about a week and back pain for about 2-3 months. I got my back x-rayed, and guess what, no fractures.
What i'd be more sold on is, something to protect my neck... that's something that you can more realistically screw up (*starts thinking about getting titanium linkages imbedded into his neck*).
Well, that's just my 2 cents on the subject, but if it makes you feel better and inspires more confidence while you're riding and you have the extra $$$ to blow, then by all means, go and grab one.