I haven't read through this entire thread so I don't know if I'm repeating anything, but...
There is a song called The Ox on the My Generation CD that's sort of a drum solo. The song sounds a lot like Wipeout, as Keith basically does a continuous drum roll through the entire song.
I have a DVD on his life (got it on eBay, questionable video quality) that shows him doing a brief drum solo on a clear Vistalite-like kit, but I've never seen it on a CD.
These are the only things I know of. You could post an inquiry on the OddsandSods discussion group - look on www.thewho.net
to subscribe. There are lots of experts there who could tell you if there's anything else available.
If you listen to those other two solos, you'll see that the Drummerworld solo does indeed sound like him. He was wild, often seemed unstructured, and his timing often seemed off when he played by himself. That was Keith.
It's well known that Keith didn't like doing drum solos (he didn't do one when I saw them live in 1973), he just liked to play along with The Who's music. IMHO he was great at that and a perfect fit for them. He's my favorite drummer.