One of the hardest Beethoven sonatas is his Appasionata Sonata. There is one technique that I know it has in common with Chopin's Octave Etude. That is legato octaves. Difference has to do with frequency of leaps. In the Octave Etude, especially the Allegro sections, it is mostly stepwise motion between the octaves. In the Appasionata sonata, it is often a leap of a third between octaves.
Here is the Octave Etude:
So you can see how I view it as preparation for the Appasionata Sonata. But will this etude help me prepare for one of Beethoven's hardest sonatas?