390s are a playful binding- good in the park and on any groomer. I wouldn't want them in the bc, but they can handle anything at a resort.
If you need something really stiff, get the targas. There are deals on rome bindings on ebay.
I disagree. While it is true that the 390s are more playful/soft than, say, the Targas, they are completely suitable for all-mountain riding including backcountry. I have happily ridden the 390s down Mount Youtei a couple of times, which is all backcountry.