I have done several this year and my thanks to Martin for excellent administration in record setting times.
They are extremely useful, for example, earlier this year to see if I had built enough fitness to ride a 400 without sleep, I did a 200 ECE either side of a 200 calendar on 17th March.
As the ECE was split between before and after the calendar, it would not have been possible to use a conventional DIY, paper or otherwise...
As that experiment was successful, I rode four more 400s :- Buckingham Blinder, Brevet Cymru, Severn Across, and The Old 240 - all superb!!
I also use ECEs when I can't get a cheap hotel near enough, choosing a cheaper one further away, and then ECEing...
The admin is pretty minimal, and easy enough, but simplification from the 'other' thread still relevant....