I am happy to provide the following information straight from one of our LCS Development Leads. Getting this information is invaluable because they know the ins and outs of the component so well they know the answer to your problem immediately.
Permission to post this information was given as long as it was posted in a manner for easy editing and I have posted it as an article. If you have any problems or questions let me know. The comments feature should be enabled but can be problematic so email is fine.
Toml LCS Kid
Excellent piece of information on the User Replicator component of LCS.
I wonder why they made the User Replicator service look for LCS enabled users in all the domains in a forest, as opposed to only looking for domains in the forest which have been prepared for installing LCS.
Eager to find the answer...
Keep sharing good information like this...thanks!!!