Interesting Trip Chris, I am excited to see the outcome, I have been interested in climbing some big mountains in the future.. and have done some messing around with gear for mountaineering.
You might be interested in this testimonial from RBH designs:
"I have just returned from Argentina where I set a new USA speed record ascent of Aconcagua. One of the reasons I was able to accomplish this was that I dropped the usual plastic mountaineering boots, and put on my hiking boots with two layers of your VaprThrm™ socks. Everything worked well as planned!”
--A possible footwear combo.. mabey some La sportiva ultralight mountaineering boots sized up to fit double RBH designs socks. (posibly bring other wool running socks for aproach, or combo with single VBL sock for diferent temps) This could be a very versatile footwear system.
--Mabey check out the outdoor designs perma gaiter on prolitegear.com.. i dont know the weight, but they are eVENT.
--Im sure you could make the RBH designs VBL clothing work for you... your clothing system could be light as a baselayer... VBL.. and synthetic or Down parka and pants.
--even if you dont go with RBH's other gear, definatly consider the gloves, the hybrid liners may be ideal for Aconcaguas conditions with a wool or powerstretch glove liner.
--the cilogear packs lok good, Golite also makes a few internal frame packs at higher weights... and if you havent seen, look at the wildthings spectra Andinista pack
--sleeping bags from Valandre, montbell, western mountaineering..
--tents, the best and the lightest from integral designs and mountain hardwear.
-- Axe: not an expert of course, but prolite has the grivel Air tech racing Ice axe.. under 15oz made from STEEL, with T-rated head, and ultralight B-rated shaft.
-- You may need steel crampons for Aconcagua.. IF kathoolas are not adequate.. grivel makes some great crampons.. Aluminum.. Stubai ultralight universal crampons, or grivel Air tech light crampons.