We typically recommend the following as a baseline:
1) Time to provision: business value generated via time savings
2) Support time: slightly different from the metric that you mentioned. Rather than looking at headcount, we focus on re-tasking support personnel who now have more time on strategic goals
3) Hardware Utilization and KwH savings due to reduction: how much 'greener' is the cloud technology
4) Backup cost and time savings: can use disk-level instead of agent-based
Cheers,
Dave