We used 6 computers each running the same patch all controlled by a master patch. If you used something like OSC timetagging, which AFAIK doesn't exist in any OSC implementations, then you could actually have pretty tight sync, and perhaps decent latency, depending on your network setup.
when you used 6 computers, i guess, each computer had his own audio interface ... there are differences between 6 computers and one computer with 6 cpus ... one car with 6 engines is something different than 6 cars :)
Remembering my truck driving lessons, i know that it's possible to have two drivers in a car. Consequently it is also possible to have two instances of PD on the same machine outputting to the same audio interface (or different channels of it), most probably using CPU time on one of the dual cores each. I wouldn't say that this is a perfect, easy-to-sync solution, though....
greetings, Thomas