This is a great string, and there will be more scout parents who will soon have the same questions. A lot depends on what is currently available on the market, and what is being closed out from last years (or the year before's) gear.

However, I thought I'd offer a couple of posts addressing questions about the MSS/EWCS gear.

http://woodtrekker.blogspot.com/2014/05/us-military-modular-sleep-system-mss.html

http://www.trailspace.com/gear/u.s.-armed-forces/modular-sleep-system-mss/

Both reviews are worth reading before you spend the money and stick your kid in one.

Personally, I really like the 2 - 2.5 lb/15 degree gear that you all guided me into, and I didn't spend a lot on it when I got it from REI on clearance.