I was pretty excited about LightTable (which has some similar ideas) when it started out, but then Chris Granger went on to another project and LightTable was l

I was pretty excited about LightTable (which has some similar ideas) when it started out, but then Chris Granger went on to another project and LightTable was left hanging. They open-sourced it, but developer uptake was slow initially and there wasn't much progress. Commits/pull requests seem to be better now (2 years on), but e.g. the blog is still very much inactive, and the last release is more than half a year ago. So for me, I'd only try yet another IDE if I have enough confidence that it will live long enough. The commitment of the original team is of course a big factor, but as was seen with LightTable and other projects, that can change quickly. So I would require that either - it is commercial and has enough investment/backing, - it is open-sourced and gets enough dev uptake quickly, or - I believe so much in the concept that I'd try it even if the other two points are not satisfied. Speaking of functionality, however, there isn't any mention of refactoring capacities. To me, that's probably the #1 feature why I'd use an IDE instead of just an editor in the first place. I'd consider the in-place partial debugging display only as a nice add-on, but nothing I would throw out a mature IDE with proper refactoring, search (for definitions, references) and other typical IDE functionality for.