I'm using the Ibex hoodie, Montbell UL down jacket (6.9oz) and a Montane Superfly eVent jacket (14.7oz) as a layering system, using a Black Rock Gear down beanie as extra warmth for the head -- prefer the hat to a parka, myself -- seems to keep the heat where I need it most, and the hoody and jacket hood can keep out wind and hold in extra warmth, if needed.
I know the jacket is a lot heavier than what most people here are rockin', but my experience is that eVent just works better than other breathable/waterproof layers, and the recent BPL tests seem to support my experience. The extra weight is worth it to me, and the price of a different eVent shell is prohibitive for the few ounces it would save.
I've been happy with a system very similar to what you are looking at. Not the lightest possible option, but incredibly comfortable and functional in a wide variety of weather conditions and temperatures.
As for sizing, I'm 5'10, 165#, and the medium fits perfectly, so sizing seems spot on. Hope that helps.