NTFS read has existed in the kernel for aeons, but write capabilities came from Paragon recently as part of a major update. It's a mature driver in the sense that Paragon have been using (and selling) a version of the driver for a long time; but equally it's rather new as their code was thoroughly bike-shedded during the submission process and what was finally merged is somewhat different from the original submission.
IMHO.. always put big storage drives in a NAS box in the network and use Ethernet not Sneakernet to move files around between devices. The expense is worth it if you value reliability of data in use (good filesystems, no USB anywhere) and survivability of your data (put the drives in an appropriate redundant disk format).