These are just some of the reasons we created the Open Game Engine Exchange format (OpenGEX):
When do you think you'll have an exporter ready for Blender? That's currently what I use since it's free, stable, highly-functional, and there are communities of artists out there with Blender models you can download for free. It'd be pretty easy to get a few models of Sintel with various animations to try different tests.
The Blender exporter is currently in development and should be available pretty soon.