I have a set of Moose Mitts that are *really* toasty. So toasty, they're too damn hot over 30-ish degrees--though it is nice to wear regular gloves with them.
I just bought some Thor Ride MX winter gloves and took them on their maiden voyage today. They are very comfortable...
For the first few miles my finger tips were frozen (it was 24 degrees). After that, they were fine. It didn't get any warmer outside for the rest of the ride, so I chalk the initial frozen phalanges up to the fact they were cold when I put the gloves on. They were fine even on the rail bed at MD, where I cranked it up to 17-ish mph (the SIR9 has gears now).
With that said, my final verdict can't be given until I start the ride with warm fingers and have toasty fingers the entire ride.
Still, below 20 degrees I'd probably use my Moose Mitts.