don't know how helpful this contribution is - but i have never found my Rab Summit jacket to be that warm - not the warm jacket that i expected. even considered sending it back to Rab for testing.
I used it in EBC in September, and suffered a bit.
maybe i expected too much ?.
there are warmer jacket.
Rab Neutrino Endurance at 650grammes is warmer than the Summit at 1050grammes, according to Rab (spoke to them last week) the down in the Neutrino is better quality.
so maybe it should be a toss up between the Neutrino and the Andes?.
what is it you like about the Summit?. the more useful technical cut, or is warmth the main consideration ?.