While most of us like to have a "matched set", it is not really necessary. In fact at one point on my NV+ since it had been going so long, I had four drives of two different manufacturers and two different sizes. I started with a matched pair of Seagate 500GB and then added a Samsung 500GB (it rejected the second as too small) so the last drive was a Seagate 750GB (of course treated as a 500GB). It ran like that without problems for about six months until the increasing size of the array necessitated an upgrade to 1TB drives (back to a matched set). Any drive on the HCL should work without a problem.
Remember - the NAS is not a backup plan.
Backup = Good, No Backup = Bad