With all due respect, this QoD is a bad choice and I wouldn't have chosen it. IMHO, QoD should introduce interesting and challenging topics, not something about picking the right syntax.
The title 'Extremely Quick Backups' is misleading since it clear to us now that it does not backup anything. And I also disagree with your statement 'It is useful to eliminate disk/network as a backup bottleneck if you need to test a system...' What purpose does this command fulfil on a test system. Without actually writing to a file system how reliable and useful is the result of such a test?
No offence, just a Friday nit-picking rant. Have a great weekend.