Exchange 5.5 migration to 2k

I am in the mist of planning an exchange 2k migration. In my research I have found that if you are using the move mailbox method and when migrating public folders, the target exchange 2k server must in a domain that is in native mode. Since it uses universal groups to set permissions.
I have checked the permissions on the public folders and they set on a per users basis (no distribution groups).
My question is....when I move the public folders, since they are based on per user permissions, my exchange 2k domain doesn't have to be in native mode right?

any help is appreciated