Just did a bit of back and forth between the stock sound and Oratory's EQ. It's pretty song (and even part of song) dependant and I think the "night and day difference" comment I made comes a lot more from the enjoyment / impact of the changes for me than the actual objective changes.

If I were to try and give a % difference in the sound I would say it's maybe 10-20% different depending on the part of the FR you're talking about but the increase in enjoyment and "fun" and other subjective aspects for me is pretty substantial. Things feel less thin and have more body and impact to them and I find it noticeably more fun to listen to even though the measured difference may be small, if that makes sense. To me the sound stage even sounds a bit wider but that could be the type of music I listen to and the dominant frequencies in them or even just a trick of the brain / ears, I'm not sure.

There are also sonic differences from person to person because of their ear canals and such never mind the mental subjectivity. So just like this hobby as a whole is highly subjective EQ adjustments are also highly subjective depending on a lot of factors.