It isn't a blurry effect, but more like a tiny bit of rainbow sparkle. It is not visible unless you look at a page with light uniform color and lowering brightness (mine is calibrated ~100nits) also help reduce the effect at a reasonable viewing distance of ~50cm. I've tuned out of the effect in about 1-2 weeks. It is like the ping epidemic here. If you use excel, I do suggest turning down the brightness. Having a bright display burning your retina all day isn't that good for your eyes.
The extra 160 vertical pixels on the 30" may be helpful, but I find myself having to turn my head more. Also 30" won't fit in your 4-800 euros budget.
PS, don't worry about response time. It is just another hyped up metric.