Yes and no...
It sounds "about" right yes but if you want an exact answer you'll have to get the manual downloaded and do some careful maths...;)
It depends on PCIe lane occupation a bit too...
The M2 drive works if you don't have PCIe 4th red slot occupied.
10 drives on intel chipset will work... two of these swap to sata express (6 drives raid possibility on ports 1-6)
And 2 more on AS media AHCI only...data storage (or one sata express) but these share with PCie grey slot...usb 3.0 blah blah so go over the rules carefully
This is hardly a board aimed at this kind of use so the question rarely comes up so people probably haven't gone into the minutiae....including myself really...:o