Whenever I see people doing something like this I remember I did the same when I was in 10 people startups and it required A LOT of work to keep all these things running (mostly because back then we didn't have all these cloud managed systems) and that time would have been better invested in the product instead of wasting time figuring out how these tools work.
I see value in this kind of work if you're at the scale of something like Dropbox and moving from S3 will greatly improve your bottom line and you have a team that knows exactly what they're doing and will be assigned the maintenance of this work. If this is being done merely from a cost cutting perspective and you don't have the people that understand these systems, its a recipe for disaster and once shit is on fire the people that would be assigned to "fix" the problem will quickly disappear because the "on call schedule is insane".