By "notice" you mean if you try hard you can detect a difference, or that it's obvious enough to affect your viewing experience? If the latter, you are either some sort of mutant with superman-eyes, or it's psychological.
http://i.i.cbsi.com/cnwk.1d/i/tim/20...tion_chart.jpg
At 80" and 10 feet, the difference is barely perceptible. Shouldn't affect viewing. To get the full benefit of 4K at that distance (assuming non-mutant-Superman eyes) your TV would need to be somewhere in the 100-110" range.