UKH

Hey guys. I'm am after a decent warmish down sleeping bag for a trip to attempt the Cuillin Ridge in June. But I'm also climbing Mont Blanc next summer and plan to bivvy so want it to be able to cope with that too.
I'm looking for 850g tops for weight, need it to pack as small as poss. Want hydrophobic down and be hard wearing.
Narrowed down my choice to Rab neutrino Endurance 200, ME xero 300, Rab neutrino 400 and alpkit pipe dream 400. I sleep quite warm and plan on wearing my lightweight down jacket over merino wool base layer if I get cold. Any advice or thoughts on my choices would be greatly appreciated. Thanks

In reply to Wooj:

All good bags in my opinion. Have you checked out PHD bags? You could lose another 200 grammes or so if that's important to you.
For alpine use it fully depends on the weather / height / exposure of where you are bivvying. This may also depend on route. For example a bivvy by the Tete Rousse hut would be very different to bivvying near the Gouter or Cosmiques huts. Getting out of the wind makes life a lot more comfortable.
I personally would be happy in any of those bags or even lighter ( but some people seem to prefer warmer / heavier ones. ) I'm assuming bivvy bag and good ground insulation / mat.
For Mont Blanc you may well be getting up at around 1.00am so you are only talking a few hours. I find that by having a big meal beforehand, hot brews, hot water in metal water bottle in bag, eating high fat foods such as cheese or sausage, doing a few sit ups, potentially adding a belay jacket over the top of the sleeping bag means I can use a very light bag.
Sounds silly but making sure I can reach my brew kit / breakfast food whilst still in sleeping bag means I don't get cold sorting things out in the morning. Personally I usually wear softshell trousers, socks, hat, gloves and baselayer top in my bag so after brew I can get up and go with minimum of fuss or sitting around. Just get up, pop on warm jacket, boots, harness, crampons, rope and go. Soon warm up on those lovely uphill slogs! Some nights I suffer but hey ho, all part of the fun.
So personally I would go for the lightest bag you can get away with, one that fits your body shape best and accept that sometimes you might get chilly.

In reply to Wooj:
For the Culins, I chose a lightweight summer bag. You just want to stay warm while you get a few hours rest. If you get any sleep then that is a bonus.

A light bag plus extra water is better than a heavy warm bag.

If you can survive in a Bivi bag with an extra fleece or down jacket then that allows you to carry more water. Carrying a sleeping bag for a few hours sleep is too much of a luxury for a bit of kit with only one function.

I found the Alps a different problem and chose a four season winter bag for the Alps in the summer.

In reply to Wooj:
FWIW I've had a RAB Quantum 400 since 2001 and find it great for everything including Summer Alpine and Scottish Winter when paired with a superlight bivvy/cover and a decent mat. However I do sleep warmer than many.

What I would recommend, especially if sleeping on snow in the Alps , is a top of the range mat, either a Thermarest NeoAir XTherm or a Downmat UL. In addition to being lighter than other options they are definitely worth the equivalent extra warmth of another 100-200g of down in your bag.

These days, even in UK Summer I'd always take the 4 season mat (an XTherm in my case) but save as much weight on the sleeping bag, or even just go for a bivvy bag and down jacket.

Thanks for the tips guys. Really good point about the mat. Currently I use an alpkit numo with a thin trimmed ccf mat to fit under my core and hips. That just incase the numo goes flat over night. I'm thinking now to go light e.g. The Rab neutrino 200 and upgrade my mat later for Alps.