I don't know specifically about the SR helmets but in general ski helmets are designed to take a large impact: when your head hits the snow, there is typically a very large surface-area of impact as the helmet presses into the snow. Whereas with kayaking, it is typically a point impact. You'll also notice that most kayak helmets are rigid and do not compress as much in an impact while in ski helmets the foam usually compresses permanently upon impact.
So, while an SR helmet is better than nothing, I would personally still use a helmet designed for skiing.
The other guys are right, There are certain perameters for impact resitance for different sports. Helmets designed specifically for Whitewater will not be at the same certification standards for impacts for skiing and boarding helmets. However if you like the fit of the Shred Ready try out the Shred Ready Phly helmet. It is designed to be both a ski /snowboard and paddling helmet. If you can't find one at your local shop drop me a line and I can get you one so you can check it out.
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