Khuja Wangtishvili Music can be mixed - maybe you should go through Herbie Hancocks discography and his autobiography book?
I've listened to the entire's Herbie Hancock discography, he used to be one of my favorite pianists but that's jazz, not classical music. When I say "composers" I mean classical music since in jazz a "composer" is a vague term, they still rely more on improvisation than note-for-note compositions. I like jazz, I even used to love it, not so much lately but it's indeed a very nice art.
Kapustin is like a classical composer trying to write notated jazz improvisations. Not saying that's bad but to me it sounds somehow artificial since it's often played by pianists who are mostly classical musicians and I can hear it doesn't sound like a spontaneous improvisation that can be made only by a real jazz pianist. For instance, sometimes there are classical pianists who play jazz transcriptions (from actual performances of Bill Evans, Chick Corea, Keith Jarrett, etc. and even I have recorded one such on my YouTube) and when you compare it to the original there's always this lack of feel. They tend to apply classical (Romantic) feel to a jazz improvisation and that messes up with the rhythm and drive. So, that's why I don't really like Kapustin.
Gershwin is different, he didn't try to compose something that resembles jazz improvisation, he rather mixed classical idiom with jazz and it's actually very good music. Not exactly my cup of teat but still.
