Well, with easyname.at we had our shared hosting application "on premise" because the second company of the owner is nessus.at which is a datacenter in the next room.
We had some advantages like defining certain internal networks, we didn't have to care about traffic limits and such there were no limitations.
It's just different since you have more control hence more responsibility, We had a complete control over the physical machines, direct uplinks to important uplink hubs. No traffic costs to consider, our own load balancers, backup machines, migration managers, DDoS protections, Mail-clusters, Server-Clusters, Application-Frameworks, Migration-Frameworks who moved customers from machine to machine without them even knowing it. Locking mechanisms if a customer got hacked .... in the end we've built our own cluster.
It is fun :) that's my experience you actually learn a lot, build a lot and it's cheap if you already have the infrastructure.
j
stuff ;)