I moved from on-prem for a school district with 5000 devices to the cloud last December. At our peak, we had 10,000+ devices connecting to three internal nodes (one primary, two secondary) that were behind a load balancer. We also had a dmz node for devices that left our local network.
Personally, the extra work it took to manage, maintain and update the on-prem servers and their nodes wasn't worth the hassle. I had to set aside downtime to update different versions. In addition, there are a few places where you can mess up the update process, and restoring a backup is a frustrating experience. Having a database restore fail because of a broken SQL entry and then working with Jamf support for 8 hours to fix it isn't fun.
Depending on your needs, you might need a load balancer and several nodes to deal with all the traffic, as well as a public-facing distribution point/node if you need your devices to get past an internal firewall.
If anything was weird with our Apple products, there was always a question, "Is it the server?" (the answer was almost always no.) Being able to remove the server from troubleshooting any issues was a big reason I wanted to migrate. Now, if there were communication issues with our server, it was very clearly a network issue.
I think if your devices leave your local network regularly, cloud-hosted is a no-brainer, but I understand some places need the granularity and security that comes with on-prem.
