Looking at option for an ultralight bag for fast bikepacking adventures.

Narrowed down to the following (but any competitors at similar price/quality considered)

Cumulus Quilt 250 - 250g fill, 480g total.
Cumulus X-Lite 200 zip - 200g fill, 415g total.

So... quilt vs bag minus hood. Seems like the bag, with 50g less fill is about 3-4 degrees lower rating.
Pertex Quantum or Quantum GL any real world differnce?

The mat will be something like a Neoair, used in a bivy (unsure which yet).

http://www.phdesigns.co.uk/minim-ultra- ... g-k-series

Well impressed with my minim ultra

By the time I add a zip the phd is pushing the budget quite a bit. Around £100 more.
Enough to get a lightweight down vest or new mat.

The quilt contains 50g more insulation than the bag and all the insulation is on the top and sides (rather than being crushed underneath). So, in theory the quilt should be warmer and in reality it is probably warmer but quilts can't / aren't tested, any temp rating is simply a best guess. My experience is that Cumulus under-rate their quilts.

If you're in a bivvy bag, use the quilt as intended and don't thrash around all night then you shouldn't have any draught problems with a quilt. The Cumulus quilts have a very deep footbox, it's almost like the bottom half of a sleeping bag mated to the top half of a quilt.

Not much difference between the shell fabrics.

If you're not in too much of a rush, I'd give FLVs post some serious consideration:
http://bearbonesbikepacking.co.uk/phpBB ... =13&t=4736

I need something for the Fiesta

I need something for the Fiesta

In that case ... neither of those

Why not?
I've used my current Vango Venom 600 1-season bag down to freezing in a one-man tent without issue and I am sure that either will be a noticeable improvement.

Why not?

I suppose it's a personal thing Matt but there's no way I'd be anything like warm in Winter with that much insulation. In my mind, a Winter quilt will contain at least 400g of down and a bag 550g plus.

I've used my current Vango Venom 600 1-season bag down to freezing in a one-man tent without issue and I am sure that either will be a noticeable improvement.

The Venom 600 contains 600g of insulation and has a comfort rating of -3

Ooops, my mistake. It is a Venom 225 that I have, ~10 years old. Very little loft these days.
600g is the total weight, or there about.

Well I've ordered my bag!

After a good chat with Peter at PHD, I've ordered one of their Autumn race bags.
We talked about doing something custom, but until I know exactly what I need and what I can/can't cope with, it would be plucking ideas from the air.

The race bag should be a good base, which I can add liners if needed.
Thanks for the PHD tip. I knew they made good kit, but having someone to speak to and give pros/cons for each was great.

I've got the PHD "racer down" which was a custom thingy for July only or something. 265g ish for 8 degrees comfort, it's nicely made and the cut perfect for use and general useability despite not having a zip. I expect you'll be quite pleased

http://www.outdoorsmagic.com/outdoor-fe ... 12936.html