Yup both are 7cm inflated although the down mat also comes in a 9cm thick version, I've got the synmat UL and my girlfriend has the downmat 7 both certainly do the job and I've been comfy with mine on snow.
Back on topic the OR ferrosi hood will just fit over a helmet but is much better underneath, the fabric is quite thin, definitely more of a heavy duty wind shell that will keep off a small shower if it needs to. The Mithril is a bit more weatherproof with taped seams and could take the place of a hard shell pretty well, no pit zips though |