Yep C4 engine has lot power indeed

For animated characters reminds me some of the fisrt games on 360 : Kameo where instanciation was demonstrated with hundred of ennemies !
But for C4 demo , have all these characters each it's own collision detction running and AI ? Not sure !

C4 have lot of top notch features indeed, but programming in C++ is not an easy way at all for 3D artists.
If it had hight level functions for blending animations and all other stuff : i would buy it directly