In reply to Jockspotter:
Depends how you want to wear it. If you're going to wear it to climb in without the down most of the time, go for something that's tight enough not to get in the way but won't restrict movement. If it's tight when you then wear it over the down, so be it.
If you're going to predominantly wear it over the down to stand around in, have a fit that's comfy for that. A bit of flapping won't matter here.
From the sounds of it, you want a lhotse in a 'large and a half', which I guess doesn't exist. I'd be looking at other jackets - there'll be one that's got the fit/space you want.
Post edited at 17:41