Finally got around to having a play with this. While RS17 still treats tags as "OR" when choosing which clients to back up in script and you can't use tags within a rule, you can use "Source Host" as part of a rule to determine whether or not a client's data is backed up by a particular Remote-enabled script. It involves more management, since you'd have to build and update the "Source Host" rules for each script, but there's a bigger problem:
Omitting by Rule is not the same as not backing up the client.
That's worth shouting -- the client is still scanned, every directory and file on the client's volume(s) or Favourite Folder(s) will be matched, a snapshot will be stored, and the event will be recorded as a successful backup. It's just that no data will be copied from client to server. (TBH that's the behaviour I should have expected from my own answers in other threads about how path/directory matching is applied in Rules.)
So if you have 6 Proactive scripts, each backing up 1 of 6 groups of clients daily to 1 of 6 backup sets, every client will be "backed up" 6 times with just 1 resulting in data being copied. That's a lot of overhead, and may not be worth it for the resulting reduced (individual) catalog size.
Also note: a failed media set or script will not be as obvious since it won't result in clients going into the "No backup in 7 days" report, since the "no data" backups from the other scripts are considered to be successful.
For me, at least, Remote Backups is functionality that promises much but delivers little. Which is a shame -- if Remote Backup was a script or client option rather than a tag/group attribute, or if tag/group attributes could be evaluated with AND as well as OR logic, I think it would work really well.