I finally made a decision on my bags, thanks to all the great info in this thread.
6' WM summerlite - 19 oz, 32*. It's a slim cut, but not as slim as a zpacks wide. It'll completely cover my head if I get chilly, plus I've got a hood if I decide to go that way. No draft collar, but a zpacks doesn't have one either, and
6' WM apache - 32 oz, 15*. Not ultralight, but still light and quite warm. Plenty long enough for me to hunker down inside if I want to be completely covered. Nice slim cut so there's less extra space to heat up, plus I can still wear a down jacket inside to lower the temp rating if needed. I love the microfiber material.
6' Marmot Coilour - 51 oz, 0*. Heavy, but I've never been cold in it. I can handle an extra lb or two when I'm camping in the winter. I'm usually car camping in the winter, but even when winter backpacking I'm never out more than one night. I hate the zipper and the size of this bag, and it's wider than I need, but it's warm and so far I haven't found anything warmer or more comfortable for the really cold nights.
For me, the pendulum has swung back the other way, and while I still value lightweight, it's not my ultimate goal (especially for sleeping). I have a tough time sleeping while camping, and anything I can do to get a good night's sleep is worth considering the extra weight.
From what I have read the summerlite needs more down to really be a 32 degree bag. I have a good friend that owned one and ended up selling it to pickup the WM Ultralite instead. If you look at how much down the summerlite has it really makes sense why people are saying it isn't warm enough. 9oz of down for the 6ft version vs. 9.2 for the small zpacks and 10.1 for the wide. Given the zpacks is missing a hood, the summerlite is missing at least an ounce of down from the neck down.
Steve, do you own the summerlite? I ask because even given what I've read and my friend's experience, it has still been at the top of my list. Zpacks and the EE enigma are both in the running as well but I've never used a bag without a traditional hood and have never used a quilt.