I run my CNC on XP. I have disconnected the Internet Gateway and the operating system is free from Internet worries. At the same time, I have access via the network to all my files which I keep on a Mirror RAID NAS drive. I would strongly recommend you do not move to Win10 for the sake of it.

The only problems I have is when the hard drive dies and I have to rebuild from backup and the last time that happened I made sure that all the files I needed (Licences, Configuration files and software) were copied into two places (one being a DVD).