The thing about Dash is that it's just so much faster at displaying documentation than going to the browser and doing a search query - I use it even when I'm online with Alfred integration.
Agreed. I started using it back when it was a free beta and bought it once that was an option (iTunes receipt says that was a few days over two years ago), and I've probably used it daily since then. The ability to almost instantly search through tons of different docsets and find what I'm looking for, narrow them down, create groupings, and so on has made it absurdly useful to me.
I make a lot of my own docsets as well (i.e., ones for GLFW 3, Gambit Scheme, JeroMQ, and so on), since kapeli was hesitant in the past to add docsets that would be only of interest to really narrow groups of people, though it looks like the user docset thing on GitHub sort of fixes that. Either way, it not being closed off to outside docsets was nice, since I imagine it would've been easy to not allow it.
Anyway, glad to see it on HN since I'm a huge fan of Dash after using it for years. Sort of a shame it's Mac-only, since I keep looking around for ways to jump to Linux, but it looks like there're some open source alternatives. So, yeah, Dash was probably the best $30 I spent back in 2012.
Certanly a great investment.