Ooh. You'll need to explain that progressive/ambitious thing a bit more. And I'd have to disagree that George's Beatle music was any more spiritual than the others. Hey Jude, Let It Be, Blackbird, Mother Natures Son, Long and Winding Road, Fool On The Hill are as "spiritual" as anything I can think of George's. And Taxman and Piggies aren't exactly dripping with good kharma.
Sorry, those old stereotype tags just don't ring true for me. I'd say Paul was every bit as progressive as John.
We had the debate last year about John being progressive, and Paul ambitious. I don't want to go over it again. At least, it fits how I see it. I just like the idea that each member had a kind of loose theme. Really, I think, of all the things they innovated, the idea of themes in music seems to be yet another one of them. The bands that followed in their wake had themes - alienation for Pink Floyd and Supertramp, Celtic and Indian fascination with Led Zeppelin, space with Hawkwind, lyrical landscapes with Yes, world music and then spirituality with Santana, etc.
But, they did cross over into each others 'territory', if that's what it was. George was obviously the most explicitly spiritual.
I think you're right about the Indian music thing being a dead end.