I so appreciate your dedicating the Rudorff postings to me!! I had just finished composing a very long posting letter in return, and for some reason it was lost during the process of posting!!
I have no idea why that happened, and it's virtually impossible to remember all the comments, but I'll try my best...I love the Rudorff Impromptu! It starts out with a very capriccious style (full of many piano pranks!) and then works into a ravishingly beautiful middle section. Rudorff indicated "Allegretto Grazioso" for this section, but (imho) perhaps "Moderato con molto espressione" might be more fitting. My evil twin (Dr. H) quite agrees with this! Alas he's a far better piano player than I am, so I listen to his playing through all the Kaun, Gernsheim, Rudorff, Fuchs; (indeed all the composers you have introduced us to) all day and night long! What a sweet gem of piano music this is.
And the Rudorff Variations I find to be superbly crafted. Very imaginative, never losing the player's interest for a moment. The title is quite fitting to the nature of the Variations presented by this work. All in all, I find Rudorff (in-mh-opinion) to be another of the forgotten piano geniuses of the past.
I'd also like to express my gratitude for your postings of the wonderful Sonatas by Franck. And I applaud your intentions to focus a number of postings on the 19th century Romantic piano literature. But of course not to forget all the magnificent post-Romantic pieces (ca. to 1930), which seem to grow in numbers the further your research takes you!
Ausgezeichnet!! Vielen herzlichen Dank fur alles wunderbare Klaviermusik...das macht des Lebens sehr gesund und immernoch vielen spass!
Dein,
Frank
(a.k.a. Dr. H. 
)