Actually N1 chap, I think it's the -535E4 you want to brag about not the -535E which was almost 10% less efficient than the PW2037 option for the 757. Only a handful of early 757s were equipped with the -535E, the rest are -535E4 which almost matches the fuel efficiency of the 2037 by using wide chord fan blades. Still the PW2037 is more fuel efficient and 1ton lighter per engine compared to the -535E4. Let's not forget how the ridiculously complex RB211 landed RR into bankruptcy and nationalization by the British government. From personal experience, flying both the RR powered and PW powered 744, what a piece of crap, underpowered, unreliable, inefficient, overly sensitive, pieces of crap the -524HT is compared to the PW4000 engines. This latest freezing fog sensitivity is just laughably far too over the top. They're much heavier, less fuel efficient, less compressor efficiency, sound like sh!t with that piercing hissing sound at idle. I've had three of them surge and overtemp and never any problem with the PW4000. Ask one of our engineers how it takes twice as much time to replace components on the RR than it does on the PW and all of a sudden the maintenance costs become a factor too which is another issue. The last three serious incidents all involved the latest RR engines. The CX A330 dual engine failure/malfunction, the A380 engine blow up rupturing the fuel tank, and now again another A330, all RR powered. Btw, if I remember correctly, Bombardier just recently announced that RR will not even be an option on the new Global Express jet they're developing which was the only engine option for the Global Express aircraft until this one. With this, RR is effectively locked out of bizjet aviation. RR is in deep sh!t financially being locked out of bizjet market, the 773ER, the real possibility of losing engine option orders on the A380... not a good big picture.
Too much complexity getting in the way of functionality, kind of like the various British versions of the English language. Unnecessarily complex and less functional than the American version.