Max I'll go is 32' due to input delay.
I tried a playing a shooter on my 60" and it was hell.
It took like half a second for inputs to register, which may not seem like much, but really noticeable and frustrating.
I have it on a 46 upstairs when it's just me. I will take it downstairs on the 75 when there are multiple peopl playing. However unless you are sitting far enough back it's a pain to pvp since you will have to turn your head to see the radar.
I play on a monitor, old habits die hard. TV can't give me what I am looking for and that is up close without panning my head left and right to see where my enemy is at.