In the past, I have done some projects of migrating whole IP Board forum to ExpressionEngine Discussion Forum. With the forum migration, its also required to migrate all the members of IP Board forum to ExpressionEngine forum.
There are some similarities between both forum systems which made whole migration easy and successful.
There is one problem while migrating the members and its password. IP Board and ExpressionEngine use different encryption technique to encrypt the member’s password due to which the same login / password will not work at ExpressionEngine end. To overcome such problem, I developed an extension hook for ExpressionEngine which lets user login with same username / password of IP Board forum.