Is there an advantage to using discreet ZFS datasets/filesystems in a single zpool?
Solution 1:
You can set quotas, compression, and many other settings per data set. Lets say you had some program or application, and you didn't want it to ever use more then 20GB, you could set that as a quota on the data set.
If you do backups or replication using zfs send, you do that per data set. So you might want to replication data from one application that you have confined to a specific data set, but you don't want to replicate the huge cache or logs for some other application. So you split things up the bits you want to replicate are on separate datasets from the things you don't want to replicate.
If you use the NFS sharing or SMB sharing management that is built in, that is also configured per data set.
So, the answer is it all depends on what you need. You need data sets if you need different zfs settings for different things groups of data on your pool.