Woah, great! Just as I wanted to factory-reset my old Vita to get rid of all traces of my main account (I got a 2nd Vita to use it, and it has a 64gb card filled with PSN games... I reaaaally don't want to get it banned).
I assumed my original activation files would be somehow linked to that account, so it's probably safer to use this activator in my case?
Not sure what's best, but I would suggest to read the disclaimers, it doesn't sound all good.
Keeping your activation files is probably the safest bet.