I've been wanting to try a Sigma Art, and 20mm works great for the stuff I do. I'm going to buy one of these once they are out.
I ordered a 20. I'm heading to Europe in a week -- I hope it shows up in time. I like sling bags, and need to carry a 5d3 with a couple of lenses.
I like the idea. More options/functionality is always better (for me, at least) than less. And I could see using the file system and networking extensions to link cameras to devices networked at home. The initial utility would relate to being better able to manage image files. Subsequent utility might be giving the photographer access to more cloud services from a camera. Sign me up.
Do any vendors have this lens in stock yet? If not, does anyone know when it is supposed to be in stock?