I don't know if anyone here investigated BFG Edition, but I have and I can tell you that it's not moddable. The workflow of authoring mods / new content is totally different and tools that you need for that are missing. It's _much_ faster than original Doom 3 at rendering many enemies with dlights (read Imps), so potentially one could have Doom like feel to it, with crowds of enemies. Oh, and the way resources get packaged, you get massive duplication of content. That's why BFG takes ~8Gb on HDD. Oh, and old menu code is not there, so you would need to buy Adobe Flash or get Flex SDK to author swf menus. Not to mention there is no documentation whatsoever on that subject (how to interface SWF with scripts in the game). While BFG is very interesting engine, optimized and fast (thanks to multi-threading), BFG in its current state is no use for modding.