Keeping in mind, when Vesper was originally released, Notes was pretty kludgey, but it was dramatically improved. So, I halfways agree with you - Vesper became less compelling after Notes got it's major rework.

I still use Vesper as my preferred "really quick" note/scratchpad taking client, even though I'm an Evernote Plus subscriber, and basically run my entire life off that App.

I think that's the major problem for Vesper - the top end of note-taking is owned by tools like OneNote/Evernote, and Vesper was never going to be able to compete in that market. People are happy to pay $30-$60/year for a world class, secure, multi-platform note taking app, but probably not willing to pay that much for a scratch-pad note taking app, when the built in one is free, and syncs well across platforms.