Yes, I am aware of some problems when using REPL_SYNC and we are still investigating it. Your logout issue I believe is fixed in the latest portal release which is 2.6.5.SP1. Can you verify that at your side?
I have created a jira issue http://jira.jboss.com/jira/browse/JBPORTAL-2044 for your problem and let me see if I can reproduce it. Please do more testing of clustered setup and report if you find more issues. Many thanks for your feedback.
Are you hitting two servers directly or through a load balancer?
Although the logout has been fixed in 2.6.5-sp1 (i can confirm that!) it's no viable option for us. As we were already in a production environment there are to many changes in my opinion (many services have been renamed for example) to use it.
As a follow up to the portlet preferences problem:
We currently working to a solution with a hardare loadbalancer, but with sticky sessions - no HTTP-Session replication and no SSO. Only the configuration is clustered with a shared db.
I can reproduce the issues without the load balancer if i adress the cluster nodes direct. Example: Three nodes (node-1, node-2, node-3).
Say i configure a (new!) portlet instance via the admin portlet on node-1 and add it to a (new) window on a existing page.
Log in to node-2 or being already logged in on node-3 (it doesn't seem to matter) the content of the PortletPreferences for the new instance from the JBossRenderRequest are NOT populated right - the "fall back" (mostly - not every time) to the standard values from the portlet.xml. They are ALWAYS(!) correct in node-1 and on all nodes(!) within the admin-portlet.
I have spent some time debugging the issue - it seems that the InstanceDefintion is not popluated correct from the TreeCache. The InstanceDefinition should contain a value like "local_51" but it contains a value like "./portletname-local" or something. I have given up at this point , we are now working with the ASYNC setting.
Your problem seems to be tied to your use case and it will be very hard (resource issues) for me to dig into it. I suggest that you use our support services and they will be able to replicate and fix your issues more quickly.
Which portllet did you use to replicate problem with preferences? If you could let me know the exact way to reproduce it, that would be great.
I tested with IdentityUserPortletInstance in a 2-node cluster as admin user. I enabled captcha support and change was reflected when I brought down the node that was active. Please let me know how I can reproduce otherwise I will mark the jira as unreproducible.