Are you guys sure the netboot port remains open on the new ip address once the game has started?
Here are a couple of tests I just did:
-In anticipation of the IP getting reset to 10.0.0.1 when booting WMMT2, I manually set the Chihiro's IP to 10.0.0.1, set up my router as 10.0.0.99 and set that as the gateway on the Chihiro. The game boots and I can ping it at 10.0.0.1 with my laptop connected to the same router. I can even push a new netboot game to it at this address when WMMT2 is booted into attract mode. Since I have no FFB hardware plugged up on the bench, I have to go into settings and turn off FFB and card reader to get the game to boot to attract mode. Once it booted, I pushed OR2SP.
-Since OR2SP is being booted on the bench, it boots to an error screen about the force feedback board, so I had to go into settings and set it to upright mode. I can ping it at 10.0.0.1 and pushed WMMT2 to it.
-WMMT2 boots and I can push OR2SP to it, rinse and repeat.
Now, on my bench testing I don't have the capacity to set up 2 Chihiros, so I will have to get to where I can test this on my cabinets to see what issues multiplayer adds to the mix, but so far if I know what the IP is going to be and have my router configured appropriately, it seems like I can still ping and push netboot games.
Pending multiplayer testing, my conclusions are that the games do not end up locking the system out of netbooting (need to test during actual multiplayer) and OR2SP is not reassigning the IP. I think for Chihiro I might be good to go because OR2SP and WMMT2 are the main games I want to swap between (and CTHR, which shouldn't cause any networking issues and isn't multiplayer anyway). I think I can get everything on Chihiro working for me in the 10.0.0.X IP range. The 2 Mario Karts are my main interest on the Triforce, and I think I can probably get them working in the same range.
Edit: Since I've never booted for multiplayer, it's now occurring to me that that each time games are swapped, there's probably going to be some test menu configuration needed to assign the right ID to each cab. Perhaps things won't be as automatic as I was originally expecting, but that's ok.