i'll agree with david,
if you are out trying to snowboard in the backcountry, and splitboard is really your only option. i snowshoed for years and can attest that it is a horrrible useless means of travel. the biggest added benefit to a split is not having the weight of the board on your back and not having a giant sail holding you back in the wind. by taking the 10lb board off your back and using it as a means of travel, you make much better use of the weight you carry. things like taking a lighter jacket/insulation cuts a few ounces max off at a clip, but the wieght is nothing in comparison to getting the board setup off your back.
i'll also reccomend the spark r&d bindings. they are the lightest setup out right now and also ride and skin the best as they are the only binding on the market designed specifically for splitting. i would not reccomend those 32 boots though. sure they are light, but when you need to use those boots for any hiking/booting they will be pretty much useless as the sole sucks. i reccomend the burton driver x's, these are the best boots out there for hiking and the stiff flex makes them manageable for mountaineering where you are climbing steep snow with crampons.
avy gear is another great place to save weight..however NOT at the expense of a metal shovel. lexan is crap and i do my best to avoid riding with those that carry a shovel made out of it. the best option right now for a lightweight aluminum shovel seems to be the deploy and transfer shovels made by black diamond. these are light and stong. avoid the huge metal shovels made by voile, ortovox, and bca...they are bulky and heavy and shovel no better than the bd. carbon probes are nice and compact, but most that i have seen are too short.300cm seems to be the length you want to get as close to as possible to, so skip the 190cm probes. i have a life link 282cm carbon probe which seems to meet the balance between light and compact but still long enough for its intended purpose. also, many times i will carry a whippit pole with me and leave the axe and crampons at home if i don't expect much steep snow climbing (over 40 degrees)..this can save a ton of weight.
besides that, the best way to cut weight is to not overpack. i carry alot more gear midwinter (2 pairs goggles, 2-3 pairs of gloves, balaclava) in the bc when hypothermia etc is an issue. in the springtime when i am trying to bag peaks etc. i usually wear a lighter shell, bring down instead of synthetic puffy, only one set of goggles and sub sunglasses for the second pair, and usually leave the winter mitts at the house opting for a set of work gloves as my backup. besides food, water, mountaineering gear, and some basic first aid survival gear you shouldn't need much else inside your pack.