Ya, lol.
The third movement of Waldstein has some ridiculous finger work that does not really come up in the earlier sonatas (obviously there are exceptions..); the fast octaves, constant trills, and just the size of the sonata comparatively...
If Waldstein is 'moderate', then does that mean that half of the Op 100+ ones are too? If you are comparing to all other rep in general, then I guess it kind of is moderate?
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Go for the Tempest, or Op 78. Both are really good! Op 78 movement 1, the second theme is AMAZING; and the second movement is really unlike anything else in the 32 sonatas; such a unique, quirky piece...
Op 90 is good!