I like a lot of webbikeworld reviews, though their site is not the easiest to navigate.
I own a set of the Cortech Scarab winter / rain gloves, and noticed they
reviewed the gloves.
While they do state that cold weather comfort will be determined by the individual user's tolerance for cold, I noticed several commenters stating that they found the gloves to be ineffective even in "cool" temperatures. I find my hands start to lose heat to wind below 50 degrees F or so. My personal record for cold hands was after a 90 mile ride @ 50-60 mph in 40 degree weather wearing these gloves.
They are tolerable for my 25 minute commute down to the upper 30s. I have commuted with them down to mid 20s, hands are icicles when I arrive at work. I have installed air deflectors on the Zero which help, but I think a set of heated gloves are in my near future. Maybe I can hold out for one more riding season : )