Looks like a good list! Just a note, are you using the Advanced Server Status page for clients primarily? Assuming you're on a VPS or Dedi, you should have separate monitoring which will alert you in other areas, not just a ping response (High CPU, space monitoring etc).
Whilst it is good to monitor the uptime (especially for clients), having a system that monitors at a higher level will enable you to solve an issue before it becomes a problem. Your clients will appreciate it