I have read most of the Q3 code and really like it. And as you said, not much (or any) overhead.

What you write about D3 (i.e. idTech4) makes me a bit sad. How comes it? Less influence by Carmack? (Because he still seems to be the pragmatic guy to me.) Too often, when C++ is involved, I see much too complicated code. Whereby I still have the meaning that you can really end up in having simpler code with C++. (Well but that goes into the usual C vs. C++ ranting discussion.)

Do you have any knowledge about idTech5 (or maybe even idTech6) which you can share?