There is one tiny little hitch involved here, which most people will not ever encounter but I ran up against it recently.
I had put a new bigger hard drive in my aging G4/400 in addition to its undersized-by-modern-standards 10 gig drive. The system and all important files went on the new drive, which was the slave.
Recently I got a new G5, and wanted to get some things off the old computer, so I hooked it up via Firewire to the G5 and booted it in Firewire Target Mode (for those not in the know, you do this by starting up while holding the T key and it allows you to mount the target computer's drive on the host computer).
Unfortunately, this apparently only mounts the master drive, not the slave, so I was out of luck there.
So. Probably not a particularly common scenario, but maybe worth a thought if you think you may someday need to use Firewire Target Mode--which is a pretty nifty technology if you ask me.