Very interesting. In monetary terms, I initially found more success with Vocal, having won 2 challenges and gotten a couple of top stories, but the Vocal gods have found shinier, prettier, newer writers with whom to play. I joined Medium about a month and a half ago and so far, so good. I'm not getting rich, so far, it's barely beer money, LOL. But, I'm in it more for sharing aspect than making a whole lot of money (although I'd certainly accept the latter). Like you, I doubt I'll hone my writing skills very much as I'm 50 now and have been writing since I could hold a pen.