These features would be nice for Carraras replicator

McGuiver

As the title says...this kind of thinking would sure make the replicator easy !
http://www.carbonscatter.com/

evilproducer

Looks very useful.

Dartanbeck

So...
Instead of adding it a feature for the replicator, create a duplication brush with its own parameter pallet.
Within the parameter pallet, the end user can add what it is that the brush paints, how the variations are handled, etc., etc.,

Put in five trees, three plants and seven rocks
Then set the scaling, rotation and depth - as well as 'chance of occurrence' duplication variables for each separately within the pallet.

Paint away.
Could become addicting!