I bought the full weather kit for my ultra-lite (2008) but have never put in on (I use the windscreen). I don't have a heater, though I have plenty of heat coming in from my footwell. I did notice that I would have to unsnap the rear of the top to get to the gas tank, would be kind of a pain.
The doors are kind of unique as they are part of the top... the snaps down the side of the windshield form the door hinge, not sure how it closes or how weather tight it would be.
I really just want a top for shade (spoiled Californian).