Awesome stuff Jack, this will be very helpful. I ultimately managed to import the file by exporting not the full profile but just the individual key directly from KeyChain, which then doesn’t force you to put a password.
One thing I would suggest also is adding back the web page with the advanced PC/Mac workflow (now it returns error 404). There are a bunch of tutorials over the Internet that make you do stuff that isn’t necessary, such as installing DeltaCopy - I was cracking my head to make that work until I decided to try without it and it worked perfectly.
Many thanks again for the reply, and I look forward to the simplified workflow on 4.18 
Best,
Alessandro