[Rover]

Then just look at 20/1.4 (950 g), 12-24/4 (only f/4, but 150 g heavier as 14-24 f/2.8), 14/1.8 is as heavy as the 12-24/4, the 135/1.8 is in the same weight class. It appears Sigma is aiming at becoming the manufacturer of heavy glass - with all the advantages you listed, Rover, but one needs to carry that weight. And the Otii are (in my eyes) only a demonstration of what is possible if you go with a manufactured (not bto) lens to the max. And disobeying details like lens covers... Zeiss sucks in this parts, but of course, nobody can see it in the pictures.

 

Not all Sigma glass is heavy, the 100-400 is a nice alternative to Nikon's 200-500. Don't take my "heavy glass" comment as complaint, I'm juts stating the weight. 

The 20/1.4 and 14/1.8 are unique(ly extreme) lenses. Half of the old MF 135/1.8 lenses used 82mm filters as well.



(so yes, there WAS once a Sigma made 135/1.8 lens... the new one is not unprecedented)

The Canon 11-24 is about the same size/weight as the Sigma (or vice versa). I'm not trying to devalue your opinion - I just point out that this is the new normal. And when 40-50MP sensors abound, you will want that last bit of resolution given by the better glass - or give up and go back to 20~24 MP where our lenses of yore are still worth anything. I'm on 16 MP and ain't complaining (yet).

 

Meanwhile in the Pentax land... "every day's tomorrow, and it's all right", to quote a DIO song.