Hi,
Dashboards are part of the management modules, which are in jar files in the /config/modules folder of your MOM, so moving dashboards is theoretically as easy as moving the jar files to the new MOM.
You should ideally preserve the folder structure of /config/modules in your new MOM,
Particularly if you have management modules in custom domains, you should be sure to copy the domains.xml file to the new MOM as well (as part of generally moving configuration to the new MOM)
Many thanks,
David