Hi Robert and Menthol,
From what i’ve searched and tried, in the Z170 ROG line, M8R and M8H are unable to set up a Raid0 config:
https://rog.asus.com/forum/showthread.php?80625-Hero-A-disappointing-Hero I suppose, reading its manual, that M8E is able to set up a raid array and, again from manual, it is unclear if M8H Alpha supports raid, because its M.2 slot and PCIEX4_3 slot cannot be enabled at same time supporting raid remapping. I think that is possible to set up a raid array in M8H Alpha using the M.2 slot and one U.2 connector (probably U.2_2).
I think ASUS, like other brands, should have at least one ROG mobo with 2 M.2 sockets supporting raid arrays, since the U.2 connector is not very friendly and usual at moment.
Some benchs with 2 x Samsung 950 PRO:
Regards