Rogue Leader :
The Hero has an ASMedia Sata controller on board and an M.2 PCIE x4 slot. If you use the fastest drives (like a Samsung 950 PRO) the HERO will support them at max speed.
I think that may be incorrect. The Ranger notes:
M.2 Socket 3 Type M
PCIe Gen 3.0 x4 mode
SATA mode
I think the fastest lanes are the ones from the Intel chipset. When all those lanes have been used, additional ones are added using the AS Media controller. The ones under the control of the AS Media controller are probably the two extra ones that the Ranger is lacking. The AS Media ones are generally slower than the native Intel ones.