I tried it once for SX3 on my sequencer-PC but couldn't realy route the Performancetool for the rewired GS3, so I kept this GS3 for other (non-Perf-Tool-Libraries).
But I think it will be still utopic to run all the SC on one machine, not to mention further GS3 Patches.
The performancepresets still do need lots of RAM at least until you finished their track and run the RAM-reduction.
So to work with several slave-PC's is still the most realistic approach to get the widest possibility to adjust the different tracks. I myself do think about adding more Slaves, to let the VI's run on other slaves than the GS3's, which may substitute, with the ProEdition and Horizon-Samples.
This makes sense especially if you want to make use of the biggest presets. If you try to do an String quartett for instance, all VI-Solo-Patches are on the same machine. but even with 3 GB-RAM you cant work with all L2 Presets of the four Instruments at once because they need more RAM (Vl: 1 GB, Vla: 0,8 GB, Vc: 1 Gb) than you can get so whatever you can "outsource" on another Slave makes Life easier.
Of course it is possible to make with one Machine a String Quartett, but that means more or less that only one of the tracks can work with a bigger Presets, the other must be reduced for that Moment. If you work on full orchestra Scores, things are getting obviuosly not easier, so the more RAM you can get for each VI, the more flexible you can make use the presets.
best
Steffen