Re: Sleeping bags.
I reckon that saying the Merlin is a 3 season bag is REALLY stretching things! I have the Softie 6 Kestrel and have found it a bit warm in the middle of summer (not this past summer! 2003 was warmer, and it had been the hottest day ) but I have been a bit chilly in it in mid April and September, even with it in a bivi-bag.
I used the No6 in a Hennessy in early October, along with the Snugpak fleece liner, and a bivi. I wasn't really cosy, the liner certainly makes it warmer, but is extremely bulky in a pack for the amount of warmth it offers. The fleece liner takes about as much space as a Softie 6, it also takes up space in the bag making it harder to move around.
If you want a bag for say late May through early September, and sleep on the ground, either in a tent or under a basha in warmer weather, the Merlin will probably work great. Stretch the season a bit or use a hammock and it may be a bit cool. The temp ratings seem optimistic if you aren't in a tent.
On a side note, I read that one company's temp rating was calculated on comfort in a tent that you are shareing with another person!! So, beware, most bags aren't rated for open air temps.
Being lost is a state of mind, not a state of place.