So, I'm looking for a bag with similar performance to the patrol bag from the MSS.  Something that will fit me (5'11", 220 lbs and like bags a bit loose), keep me comfortable by itself down to about 45-50, and and can be layered with a woobie, bivy, warm clothes etc., to go considerably colder.  I would also like it to be similarly durable, non-bright color, and at least have a little bit of water resistance on the exterior.

Now heres the rub:  I want it to weigh less and, most importantly, compress more than the MSS, which even the patrol bag by itself only smashes down to about soccer ball sized.  Costing less than $200 would be nice too.

So, the things I'm looking at:
Kifaru woobie:  Not a sleeping bag, and I'm not completely convinced by a $150 blanket.

Snugpak bags:  Never held any of them, but I've heard a few good things.  No clue which bag I actually need.

Or really anything else.

I bought a Snugpak jungle bag in the tan color. They also come in green and black. It feels a lot like a poncho liner, about the same temp rating, compresses pretty small. Zipper across the bottom, and zipper up the side. Has a mesh bug net over the face. Large enough to slip another bag inside if you want.

Are you opposed to down?

You can get the Kelty Cosmic for cheap during sales (still not terrible at retail) and it comes in 0, 20, and 40 degrees.

I have a 20 I picked up for about $120, performs great for that price and packs down much smaller than the patrol bag.

I'm not opposed to anything, but I don't really have any clue about the pros and cons of down vs synthetic.  Down is more susceptible to moisture, correct?

Not more susceptible, just less effective in it.

I only use it for the cold part of shoulder season and the winter since it is too warm in the summer for me.

The advantages are definitely weight and space savings though. I have used my down underquilt in the humid summer though and had no issues with it, just hang it to dry when you get home.

Snugpak Merlin 3