Duets order of difficulty?

[keelan]

Up for a challenge, and curious to hear if any of you have thoughts how these pieces compare for difficulty, technically and in putting together the ensemble.

Rachmaninoff Symphonic Dances
Ravel La Valse
Ravel Mother Goose Suite
Brahms Haydn Variations
Messiaen Visions of Amen
Poulenc Sonata for Four Hands

Thanks!