Ryex and F0 are currently busy with some things so they don't have much time left to work on the editor.
Technically this development build doesn't offer anything different than the previous one either. Only the underlying libraries have been changed and improved. e.g. now April properly loads PNG files again that are not using RGB or RGBA colors, Atres has been heavily optimized for text rendering, XAL has been made more thread-safe, hltypes has many components that have been improved for better performance, etc. Since I work with these libraries on a daily basis at Cateia, it's natural that they get better with time. So the longer ARC actually takes, the better the engine will work when it's finally done.