I don't care for PI Amfibs. They are ok in a specific range but they get clammy in the front under the wind barrier as they don't breathe well. You cant comfortably layer under them (other than bib shorts) so they are limited in overall range. I wore them for a few years, but IMHO they are not worth the money.

OTOH Sporthill XC pants. They rule. They cover the same general temp range alone as the amfibs but they never get clammy because they breath so well. And you can layer under them so their range is huge. I've haven't worn my amfibs since.

Sporthill XC pants FTW, it's not even close.

- edit: My opinions are based on the winter conditions here in Minnesota, if you are in a place with less angry winters then YMMV.