The Covenant required the Washington Representative to present his credentials to the Department of State, something like an Ambassador. The Delegate will presumably have to present credentials to the U.S. House of Representatives to be seated.
Practically, there's not much difference, it's even a plus because of the ability to directly influence legislation. Philosophically, it undercuts those who argue for a more independent CNMI. Former Governor and Washington Representative Froilan C. Tenorio consistently opposed having a non-voting delegate. That may be the reason, though I've never had the chance to discuss it with him.
For all of its rhetoric, Gov. Benigno R. Fitial's administration seems supportive, at least according to Press Secretary Charles Reyes in the Saipan Tribune:
Reyes noted that if the governor were to challenge the federalization law, the challenge would not include the delegate portion.
“The delegate portion is not harmful. He [Fitial] supports the delegate portion of the law. What he disagrees with are the other provisions of the law that he finds very damaging to the CNMI economy,” he added.
It would seem none of the candidates have a problem with the change.
Section 901. The Constitution or laws of the Northern Mariana Islands may provide for the appointment or election of a Resident Representative to the United States, whose term of office will be two years, unless otherwise determined by local law, and who will be entitled to receive official recognition as such Representative by all of the departments and agencies of the Government of the United States upon presentation through the Department of State of a certificate of selection from the Governor. The Representative must be a citizen and resident of the Northern Mariana Islands, at least twenty-five years of age, and, after termination of the Trusteeship Agreement, a citizen of the United States.