Hey brother,
Im pretty sure all the community settings and everything is transferred, but better get 100% confirmation from TAC. I once did move from one open server to another for a customer and we did migrate export, imported into his new mgmt server along with gateways and VPN tunnels simply worked fine, we did not have to do a single thing. The way I always recall is that PSK would only be removed if you remove gateway from the community, which does not get removed when you do migrate import (or migrate_server, depending on the version).
Andy