Megalite, or Ultralight?

Welcome, Jesse. These are two very different bags. I used to own a Megalite, and switched to an Alpinlite to extend the usable season here in Colorado. My wife has the Ultralite. I loved the space of the Megalite, but the downside is it's less thermally efficient than a narrow bag. The overfill may help somewhat, but there's still dear air space to warm. It lacks a real draft collar unlike the 20F bags, and I found that it was all too easy for that warmed air to escape through the opening. I used mine a couple of times around freezing, and felt cool – one night uncomfortably so. However it offers space to layer a down jacket underneath. I liked the shape, so I sold it and picked up the Alpinlite instead. The extra space means I don't overheat in summer (lows rarely higher than mid-50s), but I can use it well below freezing in shoulder seasons. The Ultralite will be more thermally efficient, but if you find the Summerlite warm in summer, the Ultralite may be less comfortable then. BTW, I see you posted the same thread in two forums. Only one is necessary.

I have a Megalite with overstuff, and it's a great bag, but I agree with Stuart that it is not as warm as a bag with a narrower cut. Because I'm female, that effect is even more pronounced, because the Megalite is particularly big in the shoulders — if you have very broad shoulders, you may not get as many cold drafts as I do. That said, I have used my Megalite comfortably into the low 30Fs, and I'm a very cold sleeper. In the low 30Fs, I need to use my down jacket, unzipped, across my chest, to "plug up" any drafts coming in the top of the bag. I probably should sell my Megalite and get something less roomy in the shoulders…

If you don't mind the girth of the Summerlite, go with the Ultralite. I had one of the old Ultralites with no draft collar from 2003 and it was a great bag. I used it until ~2009 until I switched to quilts.

I got a Megalite for its "shoulder room". I'm 5' 10" and have wide shoulders. But it's roomy enough for adding a puffy jacket and pants to get down to the single digits. I'll be backpack hunting in northern Nevada this month and temps could get into the teens. I have no doubt my Megalite and the EB down jacket in my avatar will be enough inside a Tarptent Moment DW. (ripstop inner)

Thats good news Eric. Can I ask what down jacket you have, what you will wear on your lower half, and what you will be hunting?

Jesse, I'm your size (6'1", 220 lbs) and loved my Megalight (std fill) for 10 years before switching to quilts…not looking back BTW. I was comfortable in the Megalight down to 15F wearing a cap4 base layer, Montbell UL down hoody and Montbell thermwrap pants. There is plenty of room in there for my Montbell Alpine light so I'm certain it could be pushed into single digits. Enjoyed reading Valerie's comments about draping the jacket over upper body inside the bag…I thought I was brilliantly inventive when I discovered that trick :) As she said, works great as a draft collar replacement.

Jessie, it's the EB light jacket you see in my avatar photo.