In other words, if I already have a system with all six SATA ports taken up (1 SSD boot drive, 1 DVD-RW, and 4 HDDs), would I have to sacrifice any of those devices if I connected an NVMe to my M.2 ...

Unfortunately, outside of using expansion cards, there's not a lot you can do if you wish to add a few more SATA drives to the storage mix. If you're like me and don't wish to outright replace the ...