So decided to test this with an extra workstation. I was able to assign static IP addresses to both FireWire ports (the first port was active right off the bat, but I had to add the 2nd one). Both ports can talk in each direction to each workstation on the local isolated subnet. But when I go to create a bond, the interfaces are not listed when I go into "Manage Virtual Interfaces." "New Link Aggregate" only shows ethernet devices - NO FIREWIRE devices.
One thing that I did find out was that 1 FireWire 800 network interface is slightly faster than 2 1 gigabit interfaces bonded. I was seeing about a +15 MBps down & +3 MBps up differential pretty consistently
The next thing I need to try to figure out is whether or not there's a way to force an aggregate bond from the shell in Terminal.
UPDATE: So I think I'm close to solving this, but I'm now having a problem where my FW800 ports have stopped functioning on one system and I have a bug report in to Apple right now in hopes to resolve it. As per my above link, I now think I can perform this on the shell (sudo networkSetup createBond bond0 interface1 interface2
)... IF it allows me to, but I can't test until I resolve this other issue.