A couple of my friends have Western bags and rave about their pack-ability as well as how warm they are for their weight so when I needed a bag for Aconcagua I pulled the trigger and bought the Puma MF. I chose the MF over the dryloft becuase it's lighter as well as easier to pack. The dryloft is better at shedding condensation which helps if you plan to do lots of snow camping and/or bivying.

I used this bag all the way up to Camp Berlin on Aconcagua (~5900m) and was completely warm and comfortable. A Western -25 is comparable to most other brands -30 or even higher (they intentionally underrate the warmth of their bags). I would highly recommend the Puma for winter mountaineering or summer climbs at high altitude (4000m and above).

In terms of fit, I'm 6'3" with relatively wide shoulders and the long (6'6") was plenty roomy for me. When in doubt, go bigger since the extra size will keep you warmer and allow you to warm up boot liners or other gear in the bottom.