I've already backed up seven ways from Sunday, but would prefer to not have to worry about High Sierra's new Apple File System infesting my external SSD boot drive. Rumor says it hits internal only? Is that true? Will updates that permit fusion drives to use the new file system to work also allow external SSD's to be reformatted? It's not that I hate the idea of a new and better file system, it's just that Apple's released a little too much beta-ware as final product these past few years. I do not want to be experimented on by something that encrypts my work, and is not very close to perfect.