In Guerilla Tactix we have upto 20 animated and 20 static models at the same time viewable with about 20.000 polys at all and its still playable with 25 - 30 fps.
I am developing a set of realistic human models. They all average between 700-800 polys. I don't see any problems with haveing up to 20 on the screen at once as long as you have a good video card.