Could it be that the Hammerklavier fugue, marked "con alcune licenze" is a kind of rejoinder to Reicha's Op. 36, about which he is said to have remarked, "daß die Fuge keine Fuge mehr ist"? What about the fugue in the D Major cello sonata, with its displaced accents and unusual structure? Could it be a riff on the compound and irregular metres seen the same Op. 36? What about the overall structure of the Diabelli Variations (a long series of different perspectives on one idea, which could potentially go on forever--not counting the penultimate section and coda)? Essentially the same fundamental structure as L'art de varier (which deserves a similar stature in the piano repertoire). Possibly the final variation, no. 33, a minuet is a reference to no. 39 in Reicha's set: https://www.youtube.com/watch?v=ks1jAMN7XTw&index=40&list=OL...
Just listened to some of this Reicha dude's stuff on Spotify and it is so similar to Beethoven thematically.
I wonder if they were both going for the same themes of ideal oneness vs. multiplicity, if they had shared approaches to exploring the space of musical theory in a neoplatonic way. Given LVB's love of wine I can only imagine they got pretty nerdy and unhinged.