The SAS controller cable came today so I took the opportunity to move everything over, it was very painless, first boot picked up all the drives aside from one which I had knocked the power out of, really like how you can lift and shift with unraid and maintain configuration.
I now have an extra bay which I have immediately added another 2tb drive to, making a total of 25TB.
Very happy with my R5 build 😁😁😁