I think Ravel recorded Gaspard de la Nuit. I don't know if Tchaikovsky was even a pianist.
Tchaikovsky was a pianist and, from what literature I've read, could play his works. How well he could play them is unknown, but considering the very scare accounts of his playing, I would say he wasn't more than "competent", as far as a virtuoso. I think it is clear he wasn't a Rubenstein, or Richter.
From all accounts I've heard of Ravel's playing, it's not great. Then again, composers playing their own works generally cause controversy - Ravel, Grieg, Rachmaninoff...I'm learning the Tchaik concerto at the moment and it's horribly unpianistic which may or may not lead one to assume he was a good or bad pianist - I know a lot of people who find Chopin very unpianistic, yet Liszt whilst hard, always fits under the hand.
I think Ravel was possibly potentially a great pianist but his heart wasn't really into performing.I remember reading an account of his teacher at the Conservatoire berating him for being satisfied with mediocre standards when he could be "the best".He would sometimes play his own Sonatine in public even towards the end of his creative life - but only the first two movements.
You mention Rachmaninoff in your short list of "controversy of composers performing their own works". Here I believe you are mistaken. Rachmaninoff was a giant, both in stature and in performing, and the digitally remastered recordings he made of ALL his own music as well as that of other composers, will testify that he was one of the greatest virtuosos of the early 20th century. His hands were huge and spanned "3 octaves" as my mom related her memories of seeing him perform.