Another vote for RTT support!
A friend sent me here to try out Corona. What a nice renderer! However I can't use it because it doesn't support RTT. :(
Lightmapping is used a ton in games because it's all precomputed so it doesn't slow down the realtime rendering, however you get high quality lighting (for static scenes).
Here's a RTT usage example, which I worked on. The whole environment uses RTT lightmaps (baked in Unity using Beast). There is only one dynamic light, right above the player character. All the rest is precomputed.
http://ericchadwick.com/img/robot_rising.htmlRTT is also used in architectural pre-visualization rendering, especially for interactive realtime 3d walkthroughs. This is my current project, for which I need a good fast lightmapping renderer in 3ds Max.
Radiosity is interesting, but has horrible tesselation artifacts. Mentalray is nice but terribly slow. V-Ray, Finalrender, etc. are usable, but expensive. Corona sounds like it will be more affordable.
Please add RTT to your feature list.