Thats true!
Pieces Im doing now and are quite comfortable with:
Chopin Preludes 4, 6, 20
Bach Inventions 1, 4, 8, 13
Pieces Im thinking of starting, although Im unsure I can complete:
Chopin Etudes 10-6, 25-2
Beethoven Sonata 1 Mvt 1
Im sure you'll agree thats it definately a big step up in difficulty. Im not sure whether I should do some pre pieces first, or just take the plunge

The thing is, I love these pieces passionately, where as something like Beethoven Op49 and 79 (suitable prep I understand) dont do much for me.