[NiLuJe]

Also, as it pertains to the original worry, (mostly, see next §) nothing will ever actually delete stuff in .adds automatically besides a factory reset, so I dunno why you'd ever be worried about updates.

More importantly, since the `ExcludeSyncFolders` stuff became necessary, actually putting book content in a non-standard folder like .adds *will* put it at risk of Nickel cleaning it up if you ever bork your regexp.

TL;DR: Yeah, don't do that on current FW versions.