When it comes to joy of using a specific lens, some people (like myself) like the weight of a bigger lens. Feels more comfortable. Smaller stuff sometimes feels too fragile in my hands and I'm mostly stressed about breaking the darn things
. Plus, I noticed (for me) that a larger lens helps me with stability when taking a shot.
I can go around with my 70-200mm f2.8 all day long without complaining.
I've always liked Sigma and this lens looks very good and seems to perform.
Interested in it and I would most probably buy one... if it would came in K mount.