The time has come for me to purchase a sleeping bag for my thru-hike attempt next year. Something tells me that the old 6lb synthetic bag my uncle gave me years ago when I was a cub scout isn't going to cut it. Of course I've been gazing at things like the Marmot Helium and Montbell U.L. Super Spiral but these are way over my budget. Basically I'm looking for a good, lightweight down bag for somewhere around the $200 price point. I've been looking at the Marmot Sawtooth, Sierra Designs Ridge Runner and Pyro and the Kelty Light Year. Are any of these good choices? There are so many options out there that it feels a bit overwhelming.
Also I'm looking at a March 20th start so should I be considering a 15 degree bag or perhaps something not as warm like a 20 degree bag? I am a fairly skinny guy that lives in a hot and humid climate so I figure the cold may affect me a little more at least until my body gets acclimatized.