>Have you seen a major leap forward in areas of headphone market?

Yes. ANC is now mainstream and quite good. The rise of the TWS is also new.

>What would compell you to upgrade today?

Nothing. I just did. Went from a DT770 to a DT700

>Have significant technical limitations been overcome recently that go beyond personal taste?

Apart from ANC and TWS? Planars have shrunken and become affodrable. Not that long ago they cost as much as a used car and required a dedicated amp.

>And how about personal taste? Was any particular pair a leap forward for your personal tastes?

Well, yes. Which is why I bought it. The Dt700