I applaud your skepticism, and you are quite right - I should not have assumed you were accepting the Visa report simply because you were questioning the Solana one. I apologize.

On the subject of verifying Solana’s numbers ourselves, you correctly ask whether their hardware specifications are accurate. I relied here on the experiences reported by validators themselves, such as this one: https://medium.com/@laine_sa/running-a-solana-validator-lessons-tips-6e6d08c0c589

My assumption that most will actually be running on more efficient cloud hardware is based on the economics of server operation from personal experience. Cloud servers are cheaper and easier to operate than co-lo hardware, therefore I assume most validators will choose that route.