This is maybe a stupid question, but your input will strongly influence my purchasing...
I'm looking for a midwest shoulder season and 3 season alpine bag. I'm all set for 40 deg F and above. I want to be comfortable in baselayers from 40 to 20 degrees F. I'm fairly certain that I'll get at least a WM alpenlite bag, but I'm wondering if I should go for the versalite which is an ounce and 10 degrees warmer... but I don't want to sweat when it's 35 degrees.
I have no concerns about opening bags to vent, but I have had the experience of sleeping in a 0 degree bag during a windy 40 degree night and it was very hard to balance venting and staying warm.
Using WM bags as a standard, what would be the "comfortable" range for a twenty degree bag? How about the ten degree bag? I'm thinking that a 20 degree bag would be not quite comfy at 20 degrees but quite fine at 40. Whereas the 10 degree bag would be comfy at 20 and just a little warm at 40, but easy to slightly vent and be comfortable. Is that about right?
I'm an average sleeper. If a loft is rated to a lower limit of X degrees, I usually find that I'm catching some sleep at X degrees and comfortable at X+10 degrees.
A long post, but any thoughts?