When some component in OP's dedicated server fails, they will find out what that extra DO money was going toward. The DO droplet will live migrate to a healthy server. OP gets to take an extended outage while they file a Hetzner service ticket and wait for a human to perform the hardware replacement. Do some online research and see how long this often takes. I don't believe this Hetzner dedicated server model even has redundant PSUs.

Anyone who thinks DO and Hetzner dedicated servers are fungible products is making a mistake. These aren't the same service at all. There are savings to be had but this isn't a direct "unplug DO, plug in Hetzner" situation.