Update on the SSHD Drive. I've attached it to my main rig and used Seagate tools to test it and its passed all tests. I've just removed all the partitions as it was a boot drive and formated as a storage drive. I'm running a different surface test now.
It its fine as a simple storage drive then I will keep it.
Other rig is awesome now with SSD installed. It even goes into Sleep mode correctly, and stays in it until properly wakened. When I was using the SSHD as the only drive it wouldn't stay in Sleep mode for more than a couple of seconds. So happy at this point. If the SSHD starts to struggle when writing large files to it, it can go in the bin.