The route we ended up going, was hybrid cloud with a colocation for on-prem (Mainframes and a few servers), and then AWS for the cloud portion. Not sure on what the cost savings were. As I wrote the authentication service I knew what those numbers were, so I knew that on a normal day we would be sitting at 1% cpu usage basically all day except market open/close. And then fiscal quarter ends were a big bump. And then of course big news days. 99% of the time for 99% of the days were just nothing.