I use the Scubapro Mk 17 as it is (really) fully sealed and incorporates heat transfer fins on the exterior of the ambient chamber.
Cold water testing has been done with it at high flow rates at 160' depth and it was the only reg in the test group that did not freeze flow during the 200 minute test.
I have personally used it ice diving with no problems at all. I have also used it extensively on longer and deeper technical dives in water temps as low as the mid thirties with no issues.
I have also used the Scubapro MK 2 and as long as you don't abuse it (excessive inflating and/or simultaneous breathing, breathing on it above water, etc,) it also does very well ice diving.
The Scubapro Mk 16 is not sealed, but has a very open ambient chamber with excellent water flow and it is also very reliable in cold water and was the choice of several PSD teams in the area who were seeking an ice diving capable regulator. However since it has been discontinued and replaced by the sealed Mk 17, the MK 16 is hard to find and unless you get a killer deal on it, the Mk 17 is the way to go.