That is right you will lose two sata ports 4/5. So the sata ports you can use is 0,1,2, & 3 with a M2 Drive. This is some what true with any board out there with a M2 port.
M.2, SATA Express, and SATA3 4/5 connectors can only be used one at a time. The SATA3 4/5
connectors will become unavailable when an M.2 SSD is installed.