Most Airlines moving towards FRMS have controlled rest in their Part A. A lot of airlines / crews don't have sleep facilities like CX. There are no scientific studies to support 3 crews are less sleepy than 2 crews (without rest facilities).
Most Pilots I know would prefer to op 2 crew and have a nap under "controlled rest" than having to look over their shoulder to talk to a third pilot who is probbaly thinking WTF am i doing here no landing and tuning in to get the cricket results.
In many situations a coffee and nap will do you the world of good when flying through the wocl. There is also a lot of scientfic data suggesting that on short slips staying on local base time is the best method to manage sleepiness thus putting a rather big ? on the rostering of 18-30hr rest periods which were previously seen as taboo.
That said 16hr in a tube is beyond the wit of man so every sympathy/respect to the Nigels up front