In reply to Gazza111:
I've a ME Snowline and it's excellent. Good quality workmanship and down seems to be lasting well. Its more warmth than I need 99% of the time, but when I was looking for a new winter bag a couple of years ago it was on offer as a special (wrong grade of down used to stuff it). Same weight, but prob a degree or 2 lower rated (still c.-20 I think).
Highly recommend it If you can find one cheap!
My wife has a RAB quantum 600 which is now about 10yrs old and still in really good nick and down is still lofting well - definitely a good sign, and would give me some confidence in Rab bags - though like Scraggygoat above says, this was bought before they shifted manufacture east and all the problems they had with quality afterwards.
For year round bothying and 3 season camping I use a phd minims 300. Light and very warm (0 degree rated). Never yet been cold in it - but it is a narrow fit, I only just fit it really!
I used to have an Alpkit bag (alpdream 700 I think) - good budget option, but I found after 2 or 3 seasons the down was seriously degraded (went from overflowing storage bag, to only 3/4 filling it). It saw a lot of use, but disappointing longevity. My conclusion was that with down, you get what you pay for. Even after having it washed / revitalised it quickly degraded. Personally, unless I was skint and had no other option, I'd give Alpkit bags a miss now and buy from a company that uses a better quality of down.
Cheers!
Stu