The Free Unknown concept is now working well for Unlimited and Advanced power, and I'm pretty sure also for both glider categories. It's still quite new to Intermediate competitors in most countries, though I guess pilots will learn the process quite quickly.
What we DO need is slick computer handling of the selected 10 (or 7 for glider) figures in each case, and both OpenAero and Visio Aresti now include routines specially written for this purpose.
To make the whole thing work well, it's important that the organiser appoints one key person to provide (locally via USB memory sticks or at some defined online location) the primary file containing the selected figures with their allocated identifying letters and maybe also their nation of origin. These can then be used by sequence designers to create and submit fully 'legal' solutions, including the correct figure identifiers, that can be either directly imported or hand-entered quickly into the scoring software.
None of this is difficult, but the opportunities for things to go wrong are all around.