Thank you for the very comprehensive reply Christopher, very much appreciated.
Thank you also for the guide to convert a WHS v1 extended volume to a DrivePool volume. I've had a quick look and it looks nice and straightforward. Will be sure to shout up if I need further assistance, but it looks very straightforward after a day mucking about with *nix systems.
No need to apologise in return, I was tempted by the drive scanner as well, so looks like a good purchase on top.
I look forward to taking the change over.
Thanks again.