I mean every piece demands complete technical prowess to play well, but do you really have to be that good to play Davidsbundlertanze at some kind of decent level?
Yes, for the whole thing. First off, you are juggling 30-40 minutes of music. That by itself is very difficult for non-advanced players, regardless of the difficulty of the music itself. As I'm sure you are aware, the challenge in keeping an audience connected to a 35 minute piece and making it sound cohesive is one of the gateways between a good and a great player.
Second off, some of the pieces are playable on its own for late intermediate or early advanced, but there are several movements which cannot be played convincingly unless you are a virtuoso. The movements in question are No.6, No.13, and No.16. I have heard grad students at my university butcher these sections and when you listening to live recordings of great pianists, these are where the most notes are missing.
I sometimes feel that Davidsbundlertanze is perhaps the hardest work in terms of the ratio between how it sounds (not so difficult) and how difficult it is to play (very difficult). There are harder works overall but none that have such a disparity in between the notes on the page and the notes in the hands.