The new iPP 12.9 might not be lighter and the 11" might be even a lot heavier if you count in the smart cover/folio and smart keyboard/folio. These things are looking like they have double the material because of the back protection than before. I choose the smart cover and not the smart keyboard for my 12.9 because of the weight difference. It weights 155 grams. If it might have double that weight the new 12.9 with a smart folio is substantially heavier than before...
Yeah I would have preferred no back protection in order to cut down on weight (I just use a skin to protect the back from scratches). But maybe it was necessary for the new two angle design. In any case, I guess it’s necessary since the smart connector is on the back now.