Dang, I like your gear list mtwarden, I'm gonna have to take note on some of your stuff. Adding 3 liters of water and your only at ~12lbs. I like!
How low do you find you can comfortably go with your current clothing system? Sleeping system? Is that a bag or quilt? I couldn't find a marmot atom "quilt" with google...
I find I have a hard time with staying warm in camp and when sleeping. I use my 10 degree bag, even when it only gets down to 40degrees at night. The worst part is my face, I could be toasty warm, buy if my nose is ready to freeze off, I have a hard time sleeping.
I suppose once I upgrade my tent, I'll have to work on losing weight from my clothing. If only I could convince the wife to let me spend more money on backpacking gear...
that clothing system is good to about freezing, maybe a little below. the exlight down jacket is remarkable warm for it's weight, layered over a ls merino top and under the windshirt, add the hat/gloves and pants and it's pretty cozy around camp at the freezing mark
the jacket (and pants/hat/gloves) can also be utilized to augment my sleeping system
the quilt started life as a Marmot Atom (long), I had Tim Marshall (of enlightenedequipment.com) convert it to a quilt. The conversion shaved ~ 9 oz off the bag (went from 26 oz to a little over 17 oz), he reused all of the fill (right at 10z) back into the quilt- so it lofts more now and probably added 5+ degrees to the bag. the advantage to a quilt is that all of the down is on top of you vs a bag where up to half is under you squashed and providing no warmth. the disadvantages to a quilt is it takes a little getting used to (if you roll around a ton, a quilt might not be the best choice) insuring the quilt is well sealed on the edges (there is thin shock cord that goes under your pad to help this
the bivy (besides providing protection from rain spray that can get under a tarp, also protects from bugs- has a noseeum screen at the head) also adds a few degrees to the effective range of your bag/quilt
I tend to sleep on the warm side of the scale, but I've been very comfortable w/ that light quilt (and the addition of my clothing) to the upper twenties
for your face, I always carry a buf in my pocket in lieu of a bandana- you can pull that over to protect your nose/mouth
I'd like to know too. And, if you don't mind, what's the contents of your first aid and repair kits?
not a lot

the fak contains a 4x5 tegaderm bandage, small roll of gauze, small packet of neosporin, package of steristrips, leukotape (for blisters), small tweezers, small irrigator and small bag of meds (immodium, advil, tylenol, benadryl)
repair kit is ~ 6' of folded duct tape, heavy needle w/ ~ 50' of 30# spectra line, few safety pins, a couple of patches for the Neoair, single use crazy glue, a couple of small zip ties and spare batteries for the headlamp
everything fits into a small waterproof aloksak
several of the "repair" items can also be used as first aid bits