I have the Sidis. They're nicely made and I love that I can wear them in moderate temps when it's wet outside because they're not super-insulated, but they are Gore Tex. That said, if I were doing it all over again, I think I'd buy the Lakes or Pearl Izumis for the extra warmth.

I found that I didn't need to size up. They're cut roomy, so my normal size allows enough room for thicker socks.