I don't know of anyone using slony-1 replication with OpenACS. If you can get this working well, I imagine there would be considerable interest in the community.
So ... hopefully you'll post about whatever you learn?
Also, how will you be using pgpools? AOLserver provides built-in connection pooling and always has, one if its very nice features. And OpenACS makes efficient use of the built-in connection pooling.
Can pgpools be used to increase the efficiency of slony-1 replication?