In my environment we have set up a stack of projects for different purposes but our custom fields are identical/almost identical across the projects.  We found that moving the items from one project to another and losing that custom data was an issue.

I have hacked the gemini_moveissue stored procedure to achieve what I want for my environment, basically I look for custom fields with matching names and custom field data with matching names between the projects and if they all match up allocate in the new ids as appropriate.

Wondering if this kind of thing is important to other people and whether my assumptions are sensible...