According to those HT TV sizing charts a 46" TV at 720 or 1080 would look the same to most people upto about 6-8' away. As the screen size goes up so does the need for more lines of resolution when watching from the same viewing point to keep the picture crisp.

Jason
M80 v2
VP160 v3
QS8 v2
PB13 Ultra
Denon 3808
Samsung 85" Q70