3D screen size ?

Yes, yes, and YES!

The 3D image doesn't "break down", but at a certain size or distance, one can see the difference between 720P and 1080P.

It is recommended that one sit closer for 3D viewing. For example, the recommended viewing distance from a 65" display is:

2D > 8 ft 10 in

3D > 6 ft 07 in

A problem with 3D can be that the 3D effect is broken / cut off at the side edges of the screen. Sitting closer helps by moving the sides of the screen into one's peripheral vision, where this will not be noticed. This helps with viewer immersion into the movie, as well.

http://www.practical-home-theater-gu...-distance.html

http://www.best-3dtvs.com/guides/bes...wing-distance/

Of course, these are just guidelines.

I happily sit 7 feet away from a 90" screen when viewing 3D on my 720p projector. Any closer and the frames of my 3D glasses would be cutting off the edges of the image. At the same distance in 2D I can see a screen door effect and the 720p image is clearly lacking resolution, but in 3D, it magically disappears.

The only minor issue with sitting so close is I can sometimes see some ghosting when looking through the edges of my glasses. If I were to move back more of the image would be seen in the center of the glasses where there's no ghosting, but I'd rather just sit close and move my head slightly when I really have to!

I tend to agree with the above, 8'-ish at 106" diag is about the limit for my glasses frames if I lean forward much at all I seem to get some cut off on the edges in 3D.