Yes, I'm aware. Threading is paramount to what I'm doing. Secondly, I'm a programmer and, though lua is nice for quick prototypes or games like garry's mod and world of warcraft, it's not a good game development language. I'd cite Natural Selection II as evidence of that. Not that it's a bad game, but a real pain to modify (hint: a lot of the game core is written in lua). No types, no good IDEs, debugging is challenging, no classes, it's just too flexible to keep organized with.
Unity has a 30-day full featured trial that you can email them and have extended for another 30 days, after that it's still usable, just without the advanced features that you really don't need for core development. I prefer Unity's limited model to this model because I can do everything I need to do, then buy the engine when I'm nearing a public release and work in the relevant advanced graphics/animation features.
Leadwerks does look promising with a superior editor toolset to say the least, but switching from lua to C++ is non-trival.
Would you be able to tell me the timing it takes you to generate the collision mesh for a single chunk in your engine as well as the number of triangles in said collision mesh?
Right, but replacing the physics system is something I can do with other engines like Unity. It's a bit of work and if I have to do it, I might as well do it in the engine I'm already familiar with.