Anybody have any opinions on the Marmot Never Summer 0 degree bag vs. the REI Magma 10 degree bag? Looking to get a cold weather backpacking bag and I think I've narrowed it to these two. I think the Marmot would hold up better, but like the REI bag because it's a pound lighter and packs smaller. Any opinions would be appreciated. I would really like to get the Mountain Hardware Phantom Torch, but can't drop over $500 on a bag.