I'm sure I'm not the only one who appreciates your detailed comparisons, so thanks from all of us.

In terms of resolution increase though, I don't think you want to think in linear terms, but area, so you need to square the increase. 600/500 = 120% per axis, horizontal and vertical. 1.2*1.2 = 1.44 = 144% of the resolution. Similarly, 8% is likely 1.08*1.08 = 1.1664 or and additional 16.64%.