Real difficult question to answer. The max poly count is the highest number of polygons that can be drawn at once without having FPS go to a critically low number. There is no real max poly number out there as it depends on the overall design of the game. Fewer particles, more polygons. Fewer models, more polygons. Optimized scripts, more polygons. The general idea is to get as much detail in polygons, particles, models, and so on and so forth and try to stay at a framerate of 30 fps, 20 minimum. At 15, it gets a little choppy, at 10, its pretty laggy, at 5, it just downright sucks. Just remember, you have to balance details with framerate.

And there is an A7 in the works. Prolly six months to a year from now before it comes out.