I'm looking to buy a winter sleeping bag not just for use locally in PA but next year during a mountaineering coarse in the Whites.I'm wondering if 0 degree would be warm enough in the White Mountains?Plus 0 degree would be fine for my other uses as opposed to buying more then one bag.I'm going back and forth between synthetic (MH Lamina) and as far as down (WM kodiak and Feathered Friends Snowbunting)Consideing I'll only be using the bag one or twice a year I lean towards the MH as far as cost..approx $350-$400.
Thoughts on my options...
Thanks,
Scott

You can't really rely on the temperature ratings of a sleeping bag - though manufacturers have recently adopted the EN 13537 standard, there are still several problems.
-The standard itself is far from perfect. Different testing centers produce different results.
-it produces 3 numbers: a men's rating, a women's rating, and an "extreme" rating. Guess which one your retailer will advertise.
-You'll often be unable to find an EN rating, especially for winter bags. The manufacturer or retailer will simply pick a temperature rating out of thin air.

All that said, I wouldn't rely on a zero-degree bag in the Whites in winter, at least not on its own. Maybe with a really tight winter tent with a stove inside, or while wearing all my layers and a hot water bottle inside the bag, if I didn't plan on actually sleeping much.

Count on overnight temperatures in the negative single digits to negative teens Farenheit. (Tonight's forecast for Gorham, NH: +2 degrees F. This winter so far has been unusually warm.) You need a lot of bag. For weight and packability, this means that real down is the way to go. The good news is it should last many many years.