Boglott's suggestion regarding Mac OS X Server seems to be one of the few options available and it's one that I'm having to consider and research.
So although Mac OS X 10.9 was free, I will now have to pay £13.99 for Mac OS X 10.9 Server and then twiddle around getting CardDAV setup so that I can restore some functionality and control over the device-to-device syncing of personal/confidential information.
I would have happily paid £13.99 for Mac OS X 10.9 providing, of course, that it had continued to provide local syncing of contacts and email account information, happily.
Incidentally, I have double-checked and my pre-upgrade clone is sporting iTunes 11.1.2 (31) with the Info tab. My post-upgrade iTunes is also 11.1.2 (31) but without the Info tab, so am I right in thinking that our missing function is still there somewhere albeit side-lined or somehow hidden by Mavericks?
Whilst I had the clone running I was able to sync Contacts as normal and tested with a minor amendment to a contact; all good. For the moment, I guess I'll just have to sync my contacts through the external USB clone (so that'll be a quick and pleasant chore compared to syncing 'the old way').
There is some obvious truth in Meg St._Clair's comment regarding the contact information that will always be out there in the wild and, therefore, open to abuse by those that would do harm. However, there are ways to limit the publicity of that information and things like opting out of the Electoral Register, signing up to Telephone Preference Services, being very careful with social media and the like, all play a part in that.
The fundamental issue is that the information in our Contacts/AddressBook is collated: contact name, nickname, emails, addresses, job titles, birth-dates etc. Having all of that information accurately related to one party is a gift on a gold plate to someone looking for a data theft opportunity. I for one would find it difficult to bear if a friend or family member's identity was lifted for gain because I hadn't exercised some diligence over the data I held on them.
It is true, of course, that just by having that information on a mobile or a computer immediately exposes that data to theft. Connecting such devices to WiFi or the internet also immediately puts that data at risk. However, there is at least some control on my part with all these aspects (eg. changing router passwords, being clued up on rogue emails, firewalls, latest OS X (uh-oh) etc).
Any argument about how simply having a computer or a mobile creates a risk and therefore I shouldn't be concerned about syncing such sensitive information to iCloud is absurd. Syncing to iCloud creates an additional risk, and it is a risk that one has little, if any, control of in terms of security.
It may be apparent that I'm growing a little angrier about this:
http://www.apple.com/feedback/ (iCloud, iTunes and Mac OS X).