In reply to olddirtydoggy:
> You could argue that feathers are feathers if they are all sourcing this Polish down at roughly 850 fill power unless you have deep pockets. Neck baffles, reflective materials, breathability and so forth all matter.
Most bags won't be as much as 850 fill power (more like 650) and I noticed a while back that Rab had started using a higher feather to down ratio in their cheaper bags. 5% used to be standard but now 10% is. Feather is cheaper, more bulky, less insulating. Also, many now use duck down rather than goose.
The game changer for me was more the mat, using the winter thermarest changed the performance.
Very true, down bags are poor for keeping you warm from the floor, a bag with a synthetic base and down filled top is a good idea.
> A Rab bag will perform very well.
Sadly, for the more affordable end of the market at least, I think Rab are now living on their name/reputation developed 30+ years ago.