On the hybrid drives that I have used.
I have not found much speed improvement using them on workstation computers.
Also, Seagate did use some of the slower drives, 5400 RPM, on the higher volume drives with hybrid SSD.
I think they also started using the slow drives also on possibly all the drives.
I also do not think your write speed is going to be what you expect it will be.
Maybe they have improved also, I do not know.
I do not think RAID will matter.
SME really does perform well on a regular hard drive.
In my testing, network configuration and network equipment used has mattered more
on a server where SMB access is the main protocol being used.
Before you load up new drives, I would try changing the NCQ to 1, if your computer drives are set to AHCI mode, and test your performance.