This worked, thanks so much!
In my case I broke ESXi doing this but only because my storage controller is not supported by the legacy driver. I reinstalled ESXi and then followed this guide first: https://www.v-front.de/2013/11/how-to-make-your-unsupported-sata-ahci.html
After doing that I was able to to disable the new storage driver and reboot into a much faster system.
Now I'm having unrelated passthrough issues, for which I'll make a new thread.
Thanks again!