Try both and see what works for you. I don't run my plugs on my macbookpro, I host them also in the VE3 instances on my external super machine. So therefore so could he. It makes for an incredibly easy setup but maybe it's not best for all scenerios. It works for mine though. The only thing I do run on my DAW is Sound Designer, but that's going to go away with VSuite Reverb anyway. Again simplifying it even more for me and taking even more load off my DAW.
This simplifies my dongles and licenses and keep them all on the slave machine with the exception of my DAW. That way I don't have to have multiple keys etc forgetting which one has what on it or losing them. You might find you like having them split up on different machines load balancing the efforts. I used to run Kontakt and Pianoteq on my DAW machine but not anymore. I do everything on the slave machine now. It keeps my DAW from ever popping and clicking and I never get audio overloads anymore.
Your G5 is more powerful then my macbookpro though so you're DAW machine is already a more powerful utility then I have to work with. Sounds like you have some playing around to do to figure out which method works for you the best.
One last thing to keep in mind with two system setups. Have a backup plan ready. If one goes down, you're dead in the water until it's revived. I lost my slave machine for 6-8 weeks due to hardware issues and needing motherboard and powersupply replacements. Covered under warranty but it don't matter. It still forced me to have to freeze tracks and spend hours of time doing work arounds until it's up and running again. But at least you will be somewhat ready for it should disaster strike you.
Maestro2be