Hello Danu,
this is not a question of advantage or disadvantage of encrypted ports. It does not depend if you want to use these ports or not; as soon as you activate SNC on the server, the server will open and use encrypted ports automatically for the encrypted traffic. Why do you have this question? Where you have found the information about encrypted ports? sapdpNNs is not used anymore, it was used in the old releases until basis release 4.6C.
Regards,
Alwina