Any key gives full access to the repo, so it’s not a form of ACL in that sense 
@x572b - two points to consider regarding backing up to the same repo:
- When pruning that repo from one of the machines, no machine will be able to back up to that until the prune is finished (which can be time consuming with B2)
- If you ever need to recover all the data of one machine, and it’s infeasible to mount over fuse, then keep in mind that you’d have to download the archive of the whole bucket which will be the size of all machines - rather than of just one machine. At your current size, this would be a negligible cost - however, for me, this was the reason I split all my servers off into their own buckets.