That exact line of thinking is how our costs increased 8x over 2 years.

And you're not immune from those issues in AWS. What happens when you run out of EBS IOPS or have to change instance type and it won't boot? What happens when your instance fails? What happens if you hit a quota limit in the middle of a failover?

AWS support is fucking awful unless you pay $5k a month or 10% of your total spend (whatever is greater) and then it's only mediocre.