>     Not sure exactly how to measure this. After installing PostgreSQL to a
> new machine, the 'data' directory is 32MB. I then restore my db from backup,
> the data directory is 1.31GB. However, the .backup file from which the db
> was restored is only 91MB.

To determine the size of your database, do this while connected to it:
SELECT pg_size_pretty(pg_database_size(current_database()))

>     Maybe up to a few dozen or so eventually.

What you must understand is that slony's communication overhead with
respect to the number of nodes increases quadratically; Every time you
double the number of nodes, you quadruple the communication overhead.
According to the docs, "Up to a half dozen nodes seems pretty
reasonable". I'm not sure what the record is for number of slony nodes
in a single cluster, but I suspect it is more than 6 but quite a bit
less than several dozen. Making Slony scale like this is a
non-starter, I would think.

Regards,
Peter Geoghegan