I picked up a medium size band, since based on the sizing chart my wrist height was exactly medium.
When I put it on though, I noticed that it gets too tight and uncomfortable when I close it to what I would see as a solid lock.
Having said that, I might exchange my band to large after all, since the only position where the band doesn't feel a little tight is when the end of the metal of the clasp is on the edge of the other side of the band and that just doesn't seem right. (essentially the rubber parts are aligned but do not overlap.
I also see imprints from the sensors on my wrist when I sleep with it, so the sizing chart might not have been that accurate (although I checked that is was scaled right).
Since this is my first fitness band and I wear my watches very loosely, I am also not an expert on how snug the sensors need to be to get good readings.
So in my case, the problem for the little discomfort is most likely the user
From a weight perspective though, the band is hardly a problem. My watches are usually heavier than the band.
Typing with it is also a non- issue for me.
Overall a quite positive experience.