I agree that the Houdini pants are def not worthy of mountaineering, but I like to use them under my softshell pants when things get cold and windy. I find that a softshell by itself is not enough for the extreme wind that the Presidentials receive. Adding the windpants under the softshells give me a warm, light, highly wind resistant layer that breaths very well. The EP pants that I have are the primaloft insulated ones so they are more for stopping or emergency bivy type situations. While it does seem like I have many layers, they each play a pretty important role for each section of the climb. More often than not it is too cold to start out in just a simple baselayer. The added wind resistance of a windshirt is def needed (this is where my Rab Quantum top comes into play). When climbing higher and the temps drop and the wind increases, the softshell comes into play. It adds a signifigant amount of warmth and protection. Once above treeline full coverage is needed. Traditionally I would take a hardshell, but the sweat gathered inside quickly turns to frost. Instead I am planning on using my Houdini windshirt. I figure it is safe to assume that 3 wind barriers could equal one hardshell. I take the synthetic fill vest along for those really cold days where you actually need that much warmth while on the move. When I make stops I pull on the DAS parka. As mentioned in Mark Twights book, I like to either add or remove a layer from the top. I do not want to mess around with rearranging clothing in the middle of the freezing woods. It is just a good way to lose stored up warmth your body has worked hard to generate.
Having only been out west a few times, I have seen that the cold up here in New England is def a different beast than what you guys seem to get out there. I am not sure which area gets the colder temps, but I think the high humidity up here adds to the feeling of being colder. On the coldest days this many layers is actually pretty sparse in comparison to alot of the climbers you see up here. I agree though, on lesser peaks up here where tree's provide more protection and the winds are not as bad, sometimes a wool long sleeve and a softshell is all that is needed. As the saying up here goes, "if you don't like the weather, wait 5 minutes"