Thanks for the tips.
The "problem" with syncing has solved itself as I didn't have time to interfere or watch the process, after roughly 12h the new node has synced completely. Now I'm wondering about other people complaining about the long syncing time from what I had the impression it could take 2-3 days. I'm not sure but maybe the connection to the "on the local network running node" did help a bit, as the hardware of the smartos box isn't powerful at all. It's a 2GHz celeron, the sia node zone is residing on a consumer grade SSD (Corsair Force LS) and zone RAM usage is capped to 8GB.
The other reason of not really moving the existing node was (still is) the impression that I can make mistakes and break it or in worst case lose the coins. I know, I can recover with the seed, but as some people tell there are problems afterwards, why should I try to break and fix things that are working? So I'll use my existing wallet only as a wallet for holding coins ("cold wallet" with seed on paper only) and play around with new ones.
A quick additional question-
is (or will be?) siad capable to work with more than one wallet? I mean something like "concurrent multiuser capability" where the wallet password is the key for accessing "own files" and files belonging to other wallets are not accessible or visible.