I would like propose Corona Painter object, that would let paint instances, like 3ds max native object paint tool does, but with all the benefits of Corona scatter. Being an object and not the tool, it would have many advantages, like containing painted proxies within, no necessity to bake instances into mesh, all the transformations would be live and all painting/erasing would remain editable. Also it would be light on viewport.
I think it would be very nice addition to an excellent Corona scatter.