Hey Triskel',
I don't know what the weather is in Boston right now but unless you're very very sensitive to cold you'll probably be fine with the silk longjohns under your pants, or nothing at all. It really depends whether you're going to be walking or standing outside for long.
I find it generally true that Ibex is nicer than Smartwool, but for me it's mostly superior to Icebreaker (for outer layers). The comparison with Smartwool is less uniform.
What I like about Ibex is that, yes, they are expensive (like the other two) but they are made in the USA for the most part. (Some is made in Hong Kong.) It annoys me to pay over a hundred tomatoes for a piece of clothing that I know was made in China for a handful of dollars, like the Smartwool stuff and even a lot of the Icebreaker now.