It seems like a piece that would be kinda a drag for solo piano or piano four hands
Just a thought, but the same thinking might have turned Ravel away from writing very successful 1 & 2 piano scores for "la Valse", "Bolero" and even "Daphnis and Chloe". At the time, and over much of the Romantic 19c era, piano transcriptions of major orchestral works were more the norm than not.
But considering Rachmaninov and "Isle of the Dead", it probably wouldn't work well unless transcribed by a great composer/transcriber (which Rachmaninov was). I really love the orchestral work, and agree a piano reduction would really need inspiration to bring the mood across, regardless of the number of hands/pianos.
Just a few late night after-thoughts.
Lontano