I'm wanting to expand my kit so I can take advantage of the 4th season and am starting to look at what temp rating down bag to get.
I tend to sleep warm, my usual 3 season bag has been an older TNF Kilobag which is rated at 32 deg. I've taken it down to low 20's in a tent/bivy with a neo-air xtherm, base layer, and a down puffy or a patagonia R2 and been comfortable.
Thinking about the Feathered Friends Raven UL or the Western Mountaineering Versalite, both with 2 or 3 ounces of overfill to give a little buffer room.
Would add a closed cell 3/4" pad in combo with your Neo. Would recommend planning on getting something that will keep you comfortable at 5F, and have additional layers of clothes that will allow you to survive cooler temps, the Versalite will do a great job at this. Warm water bottle inside the sleeping bag, a hat/balaclava, and warm socks will do wonders at keeping the heat up.
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I don't give out specific route information, my belief is that it takes away from the whole adventure spirit of a trip, if you need every inch planned out, you'll have to get that from someone else.
Have a safer backcountry experience by using the HST ReConn Form 2.0, named after Larry Conn, a HST member:http://reconn.org
Versalite should do you just fine; I think the overfill is a good idea. Clothing will give you extra margin of safety for if you are extra tired or hungry and not sleeping as warm. The Xtherm is very warm; mine is warmer by itself than the combination of regular Neoair and ridgerest, and great on the snow. Though if it is not full length you'll need another pad for under your legs. Some folks like to bring a closed cell pad anyway, both for sitting/lounging use and as a backup in case of catastrophic leak on the inflatable pad.
