Ultralight Sleeping Bags - synthetic vs hydrophobic down?

[Bobby]

I was going to reply on this thread asking if there were any new ultralight synthetic bags on the market that people would recommended:
https://yacf.co.uk/forum/index.php?topic=84290.0

However with the hydrophobic down bags like the "RAB Neutrino Endurance 200" maybe it does not have to be synthetic? 

• I want a bag for bivi/bus stop on unsupported audax events or long mountain bike events - it needs to cope with wet weather
• I don't need super comfort as it'll only be for short stops - but I also don't want a miserable shiver-fest
• I don't want a lot of weight/size because I'm crap at climbing hills anyway
• I don't want to spend crazy money

Any advice from the seasoned lightweight campers?

[Dave_C]

I have the Rab Neutrino 400 last summer from a local (Scottish) outlet for 1/2 the list price, and then got a further 15% discount for being a member of their Discount club. It is light at ~800g and comes with a waterproof drybag/stuffsack, but I don't know how hydrophiobic it is. Like all down bags I wouldn't trust it to be ok without a light bivi, outside a tent.

[Bobby]

I think I'd always have some sort of cover (most likely a bivi) - not sure how paranoid to be when it comes to down

They are a bit spendy, if I see one on a killer offer like that I'd probably get it though

[Aunt Maud]

I've used down bags for 35 years and as long as you keep it dry, you'll be ok.

With down, generally, the more you spend the higher the percentage of down in the bag. Cheap down bags have a higher percentage of feather in the mix, which isn't as good at insulating.

It also pays to have a lightweight liner, such as silk as you don't want to get the down bag dirty because they're not as easy to wash as synthetic bags.

[zomarzi]

Mountain Hardwear UltraLamina often come in the top 5 of Ul Synthetic bags various temps to chose from and reasonable. Plus with Synth. bags  if they get wet they still retain a lot of their insulation values if this happens to a down bag sorry but it's game over.
Down bags ideally should be used with some form of internal protectors either your own clothing or liners reason ? if you get body oils on internals it lessens insulation and eventually has to be washed, washing down bags is easy just follow any premier sleeping bag manufacturers washing recommendations. Use your waterproof jkt to protect your bags down or synth.