What about MultiGen? (Score 1)

I have used Paradigm MultiGen Creator for building visual databases for realtime systems and I am currently using it to build excercise areas for a Polaris ship bridge simulator. I am not sure if it is the fix to your troubles (i know for certain that it is definetly not cheap...) However it is a modeller that definetly focuses on realtime rather than fancy rendering effects. Check out www.multigen-paradigm.com