I made same comment elsewhere before finding this comment. I can vouch for this speed up in the ratio of records per page. It is very real. Only applies for small records where you can pack many rows into a page, and where you can cleanly partition by user/tenant, but that’s common enough.

I will say: we kept every table we didn’t have to migrate for perf reasons in Postgres, and never regretted it.

Edit: and the index “fix” for Postgres doesn’t work often. Postgres will validate the row on disk, even if it’s in the index, if the page’s visibility map isn’t set. If you data isn’t write once, there’s a decent chance your page is dirty and it will still make the “heap” fetch.