Carburetor heaters do two things:
1. They reduce start up/heat up time for cold engines.
2. They reduce the chance of ice forming in the carburetor throat and on the throttle butterflies.
I know for a fact that I cannot ride my Harley when the temp gets below 30 degrees because ice starts to form in the carburetor. However I have not noticed this problem with my Bandit. It is probably due to the fact the Bandit carburetors sit behind the engine (where it is warmer) and the air filter is covered. My Harley carburetor sits out in the open and I have a ram air type air filter system installed.
Motorcycles, there not just for summer riding anymore !!!!!!