Interesting that you should mention this rarity as i am torturing myself at the moment trying to play it.
The original is hard enough played to speed, then Brahms came along and turned it upside down making it more difficult, then finally Godowsky got hold of it and weaved his strange magic.
Difficulty level grade 352.
I don't know if it has been recorded. If you can wait 15 years, you are welcome to my efforts.