For anyone considering an ACCELSIOR 4M2 from OWC, the currently available versions for sale are NOT yet compatible with MP7,1. Being told a firmware update will be required, which will not be available until next week at the earliest. I'm sure the holiday will slow down a bit too.
Unsure if this is a user-end firmware update, or something OWC needs to do, or via Windows only.
Personally would only consider the Sonnet M.2 4x4 if you need verified MP7,1 support and can live with the blade restrictions, or else the HighPoint.
Right now the Accelsior is sounding way too similar to issues that presented with older OWC PCIe SSD devices that were headaches for the first several months on new machines.