You'll do better with the trigger-shifter. The twist-grips are harder to find the gear position with thick gloves on, unless the shifter has a really strong detent so you can feel it (in my experience, most don't).

I have a commuter bike with an Alfine 11 and a trigger-shift, and I have ridden it into the low 20s (F) with "lobster mitts". Shifting and brake operation are virtually unaffected.
My dedicated "winter" bike is an old Dahon Mu XL, which had a twist-grip for the Nexus-8 hub. I had a lot of trouble finding the gear positions with the first shifter, which I replaced with another one which was better. Finally I got wise and fitted a trigger-shift. I've ridden this bike down to minus-20 (F) and had no trouble shifting wearing thick gloves (lobster mitts).
Steve