I have worn Nepals for 12-13 years. I wear a single mid weight Smart Wool sock in the boot. I use them for Ice climbing from New England to BC as well as year round mountaineering in North America to Nepal. If it is going to get cold ( -10 or colder) I put on an insulated super gaiter. I wear Charlet Moser M10 spikes for ice and Petzl Vaseks or Sarkens for mountaineering.
I would suggest not getting them too snug or you end up with black toenails midway through the climbing season, on the other hand a heavy weight sock may allow your foot to slop around in the boot, kind of defeats the purpose a good boot.
Info on gear, conditioning, and preparation for hiking/climbing.