My apologies if you thought I was making an outburst...
Only an outburst about how good those sunroofs are!
I have driven a few Coopers with the sunroof:
A. The performance is excellent.
B. The car handles like a roller skate
C. The newer cars have eliminated the squeaks and rattles from the early production models.
D. If you are in warm climate like Oz, make sure you have aircon as they will let a lot of warmth into the car.
But sorry, I don't have the info on how much they add to the weight of the car.