Viewing angle that important on LCDs?

I currently have a Samsung monitor with 170/170 viewing angles. I'm thinking of upgrading to a bigger monitor, but it only has viewing angles of like 140/135. How likely am I to notice this difference? I notice it sometimes with my current monitor - if I slouch in the chair I often have to adjust it a little bit - same thing if I sit up really straight or am standing.

It seems to me that it would make a big difference, but I thought I'd get some opinions.