I am 5'10" and in reasonable shape.
I thought I needed a X-Large for the winter clothing - there was no need so I exchanged for Large.
I tried it for wall climbing and used it for ice climbing at the Ouray ice festival. Good and reliable, easy to put on and very light weight, easy to carry ice tools and ice ax if you do not carry a pack.

I used it a couple of times this winter mostly below 0F.
Tried it at Longs Peak Boulder field with Bibler Tripod bivy and The North Face Himalayan Jacket and no sleeping pad (wind took care of that one)... I am not sure about the wind chill outside it was below 0F in the bivy. I would not need the Jacket if I had the sleeping pad. Sleeping bag is roomy and very warm... The only problem is the stuffing sack (which I did not even try). I got an x-large OR compression sack. Even that one needs some work... I also have a Helium. I think The North Face Himalayan jacket and helium is the light-weight alternative for me.

Very warm. These are my first mittens after a number of gloves. If you are active you will probably need to take them off from time to time just to cool your hands. It does not have the perfect grip of a glove - you should not wear at the arrest hand during bailey. OR mittens were a bit expensive for me and you probably do not need water proof for the temperature range you will use them. It is roomy and you can easily fit an inner glove (setting up a tent, etc.).

I tried it once with my La Sportiva Trek boots, probably did not secure it properly and they came off after 50 yards on irregular snowy, icy, rocky surface. I have step-in crampons and I prefer the security of those. I will try it again just to verify. They are relatively light and seem to be strong.

I am 5'10" and in reasonable shape and I got a Large. I did not need a larger size for the water bottles. Shell is durable, and has many pockets. I wore it a couple of times: At Longs Peak under high winds it is really warm and you do not feel the wind chill. I had some problem with the hood at first but after you figure it out it adds a lot to your comfort. I had a -40 degree bag. As a light weight alternative you can probably go with this parka and a 15 degree bag in a bivy. The only downside is that it lacks the ventilation zippers under armpits - unzipping is not sufficient when you have a pack.
I also wore it at Ouray during baileying for ice climbs. Minimum movement+cold=great comfort. This is my first down jacket and it is money well spent.