Yes, they will work like SAS2 drives.
Took a quick look and they don't support dual link, there's an out for daisy chain or you can use the second module for redundancy (not supported by Unraid), so for best performance you want to connect each MD1200 to a SAS wide port on the HBA, so get a second HBA or one with 4 ports, bottleneck then will be the PCIe 2.0 slot of the H800, if the board/CPU supports PCIe 3.0 it would be faster with one or two PCIe 3.0 HBAs.