Eric, for troubleshooting replication issues, there's really no substitute for going through the replication troubleshooting series I've posted on this blog. These articles focus on 2003, with the fourth one updated for 2007, but all of this still applies to Exchange 2010:
Part 1: http://msexchangeteam.com/archive/2006/01/17/417611.aspx
Part 2: http://msexchangeteam.com/archive/2006/01/19/417737.aspx
Part 3: http://msexchangeteam.com/archive/2006/01/23/417974.aspx
Part 4: http://msexchangeteam.com/archive/2008/01/10/447843.aspx
I would mostly focus on Part 4. It describes some common issues with replicating from 2003 to 2007, and our common issues replicating 2003 to 2010 will probably be very similar.
Troubleshooting public folder replication can be pretty complex, but these articles should at least help you to identify the exact point of failure.
Milind, glad to hear you have found the tool useful!