Emirates chose EA engines over Rolls for its A380's. They are unwise, and don't know the value of Fuel??
Bearfoil,
I don't know where you got this idea.
Compared to the Trent 900 on the A380s, Emirates are way ahead on sfc and block fuel on their aircraft, to the degree that Airbus is producing/has produced a new Performance Manual (by whatever name Airbus uses) to take full advantage of the actually achieved figures.
By comparison, the Trent 900 ( and traditionally since the RB211-22D through the -C,-D and -524) is still well below book figures and contract guarantees.
Incidentally, the "short" cowls of the various RB 211 produce some quite interesting drag problems, particularly above M0.855, not so the CF6-80C2 on many B744 and B767.
In every weight comparison "like for like" the RB 211 is heavier than the GE or PW equivalent, a function of the "three spool" design.
I would check the weight claims of the Trent v the rest very carefully.
All publicly available information.
Tootle pip!!