I own both the Pearl Izumi Gavia and Sealskinz gloves.

PI Gavia are good from 10 C down to 0 C unless it is raining when they are useless but they are very thin and easy to ride in.

I bought the Sealskinz 2 weeks ago and my initial impression is good. They are thicker and a little harder to ride in (but really not bad) and a lot warmer than the Gavia. Unfortunately I haven't used them in the wet so can't help there. I wouldn't wear them if it is over 5 C though, too warm.