*I* would rather have another box coupled with the two *now* to test our load distribution concepts then another toolserver. Daniel, feel free to bash me for that :)
I as a tool author 'd like to have a toolserver with r/o (or if it's possible r/w) access to an Rendering/PostGIS DB as well as r/o accedes to a (as complete as possible) OSM-DB clone - may it be named cassini, willow or nightshade or whats-o-ever.
So if all toolserver *must* be separated from the live boxes, maybe cassini can be the db server to nightshade & willow as ptolemy is to ortelius..
Peter