*Draft*
If you have a situation where you have two or more Jira Servers that you want to combine into one, then you are kinda stuck.
There is no easy way to move projects/issues between servers.
The main reason is because of the intimate relationship projects have with everything else in the system...
We looked at a number of ways of doing it - but settled upon working with the XML export - merging two together.
Its quite tricky, because you have to deal with duplicate enities (like Default Permission Scheme) as well as incrementing primary keys, and maintaining the mapping between entities...
Its nearing completion - will post more documentation when its completed.