I'd note here, too, that Bruce Hornsby was actually able to push the Dead, particularly Garcia and Lesh, into comparatively structured improvisations. Indeed Hornsby is the Dead keyboardist who reminds me most of Page, though Hornsby has stronger chops and Page sometimes recalls Keith Godchaux in his clomping rhythm approach...

There's an amazing but poorly-titled compilation floating out there on the Internet, 'Jamming at the Edge of Magic' (presumably named after Hart's book), featuring sparkling 1988-95 improvisations; the Hornsby segments are the most chromatically interesting and structurally intricate by a large margin. He gave Garcia a great density of material to work with, which brought the best out of the guitarist. Ironically, H is both the jazziest of the Dead's pianists and the most 'post-Dead,' if that makes sense.