It's still a great original post though!
How about a "gateway" Application on the main DAW machine. I am not a programmer so I am guessing here, but it would seem possible to run a VSL type mixer on the main DAW, that is receiving all the audio from all the various slaves on the network. This "VSL Mixer Ap" would then slave to the sequencer running on the DAW, perhaps as a locally connected server.
In effect, this "VSL Mixer Ap" would hijack all the ethernet streams being received by the DAW machine, and create a submix. It would host pugins etc etc. Perhaps this "VSL Mixer AP" could be running on one of the slaves?
The point is, professional users like myself and the original poster, are spending much too much time "hunting around our slaves" to work out what is what. At the same time, maintaining templates so that a whole bunch of sequencer projects can be loaded quickly. The ability to have a "mixer" up and running all the time would be amazing.
In fact, it crosses my mind to try this approach dusing another copy of Nuendo or something on a machine, and spit the submix to my DAW via ADAT or something. Worth trying out at least to see if the work flow makes sense. I know I am tired of hunting.....