I'm so skeptical of this, there's about the same ratio of people saying that a system transfer DOESN'T unban the source system, and people saying that it DOES unban the source system.
Personally, I don't see how it would unban the source system, because it's not like it's getting a brand new device id, ctcert, localfriendcodeseed, etc after transferring, right? that wouldn't make any sense from what I know
I'd really like someone to prove whichever side they stand on, be it that it DOES unban the source system, or it DOESN'T, because right now, how I see it, based on how things are supposed to work, it shouldn't unban the source system