Avgenie
Don't believe what you read. Very few books are without some kind of agenda.
For companies that do the long treks FOUR engines always will be better.
Airlines like JAL, Singapore, Qantas and South African.
The 747-800 is, in my opinion, THE global proven airframe, as long as it has GE/EA/PW engines.
I would suggest you look at the routes they take. Oceanic operations. Before someone chips in with ALL the other operators who use these routes with ETOPS I would remind that for the above noted the routes are the "bread and butter" everyday revenue provider.
Turbine D has convinced my brain FOR Etops but not my intuition.
The Asian Steppe is like the Moon.
Regards