Ondine?
Rachmaninoff Prelude in C-sharp minor. The first three notes.If you miss those(especially the C sharp) it will be so ridiculous that probably you wont play the piano ever again.
Le gibet is more dangerous cause that sets the tone for the entire pieceWell both of them do but IMO it's a lot harder to recover if you mess up the first b flat in le gibet.Additionally I always thought the right hand in ondine is overhyped in difficulty
Sure. Maybe the whole Gaspard is overhyped for difficulty ...
Well I've played the whole thing so my opinion is based off actual experience and not just looking at the score and listening to recordings. Especially if you're in a hall with echoey acoustics you don't have to play all the notes. It's just an effect. As long as you get the general idea you're fine. But you're often at the mercy of the instrument you're playing on and it has to have good balance.
Beethoven Op 81aSure, the beginning's easy, but it's the most important phrase in the entire piece, and you are so exposed.
pretty much true for any piece