In reply to niki:
Hi Niki,
I have a Rab Expedition 1000 bag but I am currently selling it on ebay. Its not that its a bad sleeping bag as it kept me warm at -18 in Nepal. The bag itself is manufactured so you could if you wished wear a down jacket inside the bag, for example, at high camp on Summit day. Because the expedition bag is slightly wider at the top I found when I wore just a base layer to sleep in I got cold spots around my back and had to tuck the bag underneath me. I would imagine that this problem is reduced for a heavier person as they would fill the upper part of the bag and reduce and 'baggy' spots. Another person on the exped had the same bag and had no complaints as I did.
I can only advise to try the bag before you buy it. Actually take the time to get in the bag in the shop, wearing both t-shirt / down jacket etc to see how it fits. For me personnally it kept me warm down to -18 but not without adjusting the way I slept inside it. For me it was too much of a comprimise.
Hope this helps
Steve