Comment by necovek

The benefit of a big TV should be that you can move it farther out than the 6" you mentioned (and that the person is roughly sitting at), increase text size, but need fewer neck movements to take it all in — provided you can focus at bigger distances.

You are essentially keeping the same angular size, and by moving an 85" TV to 19" from your eyes, you get text to be sized just like your 27" at 6" (3 x 27" = 81").

Won't help with your neck issues though, since you'll have exactly the same issues.