emailsfh wrote an answer about Rab Neutrino Endurance Down Jacket - Men's on February 20, 2013
For anyone wondering, I was able to try a small and a medium. The small is a bit too snug in the chest, even with not much on underneath. I would say RAB runs a bit smaller than Patagonia and the ranges that Geoff gave above are fairly accurate. I'm definitely in between sizes here, but for this kind of jacket would size up for this brand if you are in a similar situation.