Thank you so much for posting that pdf, that really should be posted somewhere on that site because without the context just throwing out "it's git without a staging area" seems like a pretty poor argument. After reading the whitepaper I would still say that I'm not sure there's much value in the project, that being said they did manage to simplify the "mental model"... although honestly not by much. I'm not sure the cost is worth the benefit here.
No problem, BTW, in my mind it's getting rid of the (need to) stash and improved management of untracked files that are the major simplifications, not staging.
In my workflow I also see no cost, but I am happy to accept that that's because we don't have very sophisticated needs.
