Closed source is less of a problem for me than the draconian licensing. Paying such steep costs to use in production is a no go for me. I could afford the $1500 personal productivity tool fee for just myself, but then none of my coworkers can use anything I write which probably doesn't help advertising. I really like the symbols more than J, but J ends up being more practical for me. I think if array langs are to take off, kx systems would have to make their software free and just charge for support, but I doubt they'll do that with how much money they're making.