Yeah no you are reading it correct. Routing option has not changed its purpose as far as I know. I think a workflow has to be associated to the selected LC also. It was not specified if ProjectLink was installed? I kind of assumed it was but asked indirectly. Think there are actually two concerns in David's email. Waiting for him to clarify.
On the multi org and site level issue, if you want to move data between organizations, suggest you load at site level a LC also defined at the particular org levels. A workflow could move the object and reassign for you. Domains are your biggest issue. I think once data is created its not your lifecycle per se that is the problem, but rather that the data has retained a reference to its originmating domain in lifecycle template iteration and the object itself. If you have access as a user to both domains in at least read capacity moving existing data shouldn't cause an issue.
If the destination organization roles and principals do not have access in source organization, you are in for more work.
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