If you want to go white gas - the Simmerlite is about as light as it gets. I use one for my snow camping trips. The Whisperlite is almost as light and from my testing of the two stoves it is slightly more fuel efficient, so if your trips are like a week or more then they come out about the same for total weight including fuel.
I am thinking of switching to an inverted canister stove - just ordered one of these: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=130448000460&ssPageName=ADME:L:OC:US:1123
But I do not face temperatures as cold as you will. My understanding is that even an inverted canister stove is not so good below about 20 or 25 below zero, and you might find yourself out in that kind of weather in Minnesota. White gas definitely will do the job at those temps and below.
I have played around with the numbers a lot in considering whether to switch stoves from my Simmerlite, and the difference in weight looks to be really small, with the canister stove slightly ahead on short trips, and the white gas stove becoming the lightest on a longer trip due to the fact that you can carry extra white gas in a plastic bottle, while the weight of the additional canisters is unavoidable. This is assuming your cuisine is as simple as mine - I light the stove once in the morning and once at night. If you tend to relight your stove a few times each meal, then the canister stove gets the edge since you don't have to use up fuel re-priming.
So my conclusion is to consider the weight about equal, and make your decision on other factors - convenience, safety, performance in extreme cold, reliability (canisters win that one), etc. White gas does cost less, but unless you're going out every weekend the cost isn't much anyway.