The gear list in my profile is one I used in January in Vermont. Very similar to my gear list for ADK mountaineering. The only thing missing is crampons and Ice axe and at WMS there are always 2 instructors per combo group so we took my Shangri-La 2 last winter. I am also dropping the VBL clothing I think. I am going to be making a few changes this winter, but nothing overly dramatic. The big thing to remember is that winter light is just like summer light, every item weights something bring the smallest lightest item to do the task you need. The gear list on the website is one they have been evolving for many years and have it dialed in very nicely for beginning students. After going through gear check in last year it became very evident that students base weight went up when they insisted on bringing backup clothing or extras like a large first aid kit, or lantern... The big ticket items to be conscious of are:
Pack - many expedition winter packs weight more than 7 lbs
sleeping bag - either buy or rent a high end bag, it is not only pounds in weight difference but total volume inside the pack is hugh. The bare minimum bargain bag I would take is the REI expedition down bag at a little under 4 lbs. You have to spend twice that much to get a bag about half a pound or so lighter
Extra clothing - I see so many people carrying 2-3 fleece layers. One high quality down or synthetic insulation layer will serve the same purpose at 1/3 the weight.
The cost of these three items is very high but, in my opinion, that is the difference between 20-25 lbs and 40+ lbs.
If you decide to sign up, stick to the gear list and set a budget for what you want to buy and what you want to wait until after WMS to start buying. You can easily spend hundreds on all the little things you "need" for WMS but in my opinion that money should go towards a lighter pack, sleeping bag, or quality insulation. All the little things most people already have they just don't realize it until they get home from winter school after seeing one of the instructors or another student using the exact same thing that was replaced and is sitting on your gear shelf at home.
I would wait on buying all technical gear and boots. Renting boots may suck for the first trip but you will find out quickly that unless you are climbing Denali you may not want plastic boots. I haven't worn plastic boots since I was in the 5th grade the one time I went skiing, I dread the day I have to get them for an upcoming climb. The other technical gear has alot of preference or specific fit that you want to wait until you have tried a few things. For instance ice axes come in all lengths and weights, with a grip, without a grip, different points... Rent/borrow a few different styles and lengths until you figure out what you like. Crampons are so boot specific that I recommend buying them at the same time. I made the mistake many years ago of buying my crampons on the internet, the fit on my boots is ok but I would like it to be better and they weight a ton. I can't do anything about it now until I wear out my current crampons or boots.
I am hoping to in the next few years of instructing work up a lecture for one of the nights on lightweight/making your own gear. There are several lectures on different instructors gear philosophy which is what makes WMS so interesting. There is time built in to pick the brain of any of the instructors on their specific gear choices. Without ruining some of the fun, I can only think of 2 pairs of the 15 or so instructors that have the same gear philosophies. And 2 of them are married so they share a whole lot of the same gear.