I only recently started using but I'm still using it in it's "trial" mode, was planning to purchase later but your point actually makes me wonder. So far tho, it's been excellent and for my needs - amazing replacement for my previous IDEs, yes I know, technically ST2 isn't a "full IDE" :)
I am in the same position where I planned to purchase it to support to the developer. I am worried that there is no further development.
development is most definitely ongoing. There is a new dev build almost every week.