Replicating only a particular database - Londiste, or Bucardo

I have been using Slony-I for PG replication of a particular database in a cluster, while a second database is local and not replicated. This works fine for small number of nodes. But as we are moving to scale - say around 30 nodes, we are seeing that Slony-I replication will not be able take the load - guess since now it would be maintaining a mess of 30 nodes.

PG9 logshipping replication is out of question because it works on entire DB set. So I looked at Londiste, Bucardo. Here are my requirements I would like to know if either of the two would suit well

- nodes are added on the fly, so first it starts with one node and then some network admin comes and adds another node to form a Publisher-Subscriber node and then adds more nodes(or drops nodes) to have multiple Subscribers. it is a master-slave replication
- promote a subscriber node to become the Publisher(Slony-I does it slow here as it has to figure out which one in the mess has the latest copy and then finish some replication)
- if a node is not replicated for sometime(6 hours for Slony-I) it is dropped from the cluster

We have scripts for Add, Drop, Promote and Reset(a single node when it fails/we want to join it back)

So my scripts have to be modified for the new replication model, but will I be able to achieve all the above with Londiste, or Bucardo. Or else, is there any better thing which somebody is already using with a model like this ?

Thanks,
Lalit