I have found that i do have problems with the jet boil in the winter. So i have been looking at a MSR whisperlite universal. I hear that the ability to inver the canister helps the system run better in the cold. However by biggest two issues with my jetboil and almost every other canister stove I have found is
1. it requires you to keep a very close eye on the burner at a low setting. if you are running it at a low setting it will "wink out" after a minute. This make keeping something at a boiler but not over flowing very hard
2. There is a definite lack of adjustability in the burner control. For a few handle that has four to five turn total range its usable adjustability range is about 1/8th to a quarter turn at most. Very annoying to get the right amount of heat.
I find my snow peak pretty good on both those counts. I definately don't need to baby it when on low, and it adjusts well for me from anything from a slow simmer to a blast.
I'm looking at a few stoves: I may end up getting them all but tell me what you think.
First one I like is the Soto OD-1R Micro Regulated Stove, this is a canister stove. the major feature I love is the regulator. this sounds like it would solve at least my first issue with my jet boil. I also think I could carry my jet boil with me and use this stove with it.
Second ones is the MSR WhisperLite Universal Stove. I like the fact that is can do both cans and white fuel. But I haven't seen it in action and I don't know how it work in respect to my 2 major problems with the jet boil.
My three cents? depends on you - I'd look at the snow peak if you haven't - I find it doesn't have the problems you describe - for a general small canister stove the soto looks good, but has a burner pattern I generally don't like (affected by wind!)
Were I buying a new whisperlite - I might buy the universal, but I think it's a bit too heavy for me for a canister stove - so while it's "nice" that it can use canisters I can't see it as a feature I'd use.. the new one "appears" to simmer easier than the old one.