I don't know what grades they are, but they are advanced. I am guessing that grade 7 is very advanced: Stravinsky - Three Scenes From Petrushka Debussy - L'Isle Joyeux I hack out both, and although I'll never play these perfectly (or even well) they have taught me an enormous amount about technique and theory. Actually I only hack out the 2nd movement of the Stravinsky - "Chez Petrushka" (Petrushka's Room). BTW - I also have the music for the first promenade of the Mussorgsky - that whole suite is a challenge harmonically and rythmically, and well worth the effort! If I had the music I'm sure I'd abuse several of the pieces, especially "Bydlo" (Polish for "Ox Cart" I believe) and "Baba Yaga's Hut" (second to last movement).
12th June, 2017