Of transports suggest icq.jabber.sk. There is a downside: no delivery report messages. But a big plus: absolute stability (I tried this one the most). Contacts adequately imports — substituting Nicky.
What about the transition from one transport to another can advise one thing: before registering in the new transport set Psi+ (maybe there are other messengers with an advanced contact Manager) and the Manager please replace the old domain all contacts to the new one. And then recorded in a new transport (not forgetting to disable manual authentication, though I can't remember, maybe it's optional, but better safe than sorry). Not so sure, maybe Nicki will be old, that is, will be absent.