instance store on aws can give up to 3.3mil iops https://aws.amazon.com/blogs/aws/now-available-i3-instances-... - the main problem is just using networked storage.
The per-disk performance is still nothing to write home about, and 8 actually fast disks would blow this instance type out of the water.
Which means you can count on it about as much as a server of your own, if you could not repair the server.
I know a database company that uses instance storage as the primary storage. It’s common.
That said, a good bit of our environments are scheduled, so it still wouldn't be an option there without hacks (e.g. doing a compressed blockwise dump before shutting down and then a blockwise flash on startup).
The NDA prevents me from saying which database company, but it’s a major provider of cloud managed databases across clouds.