I am a demanding user, I accept (hundreds of contacts, thousands of appts).
However, this missing sync is marketed as a golden shilling,
yet fails to be worthy of any place in my pocket.

I did get a refund, which is something.

Specifics - Crashes, failures to sync, duplications (try deleting over a thousand duplicate entries by hand), and errors in syncs are just the start of it all.

Don't buy it, and if you do, make a hell of a stink to get your money back at the end of the day.