Sleeping bags. Yawn!

Already looked at most of the recent threads on here about this.

Spent a chilly night last weekend on a hill in the Cheviots in my 25 yr old 2 season synthetic bag so fancy something warmer, lighter and smaller to spend my birthday money on.
Current bag is 1kg roughly and packs to 18x34 approx though would probably compress smaller.
I'm 190cm so it needs to be long
Down because it'll be used mostly for single nights and I think hydrophobic down, waterproof outers and care will be ok.
Budget about £250
Looking at:
Mountain Equipment Helium 400
Rab Alpine Pro 400
Rab Ascent 300
Alpkit Pipedream 400

Possibly some Mammut ones?

Anything else?
Cheers