OK, here is some engine comparison data for all to mull over:
Three spool vs two spool
B-777
Trent882
Engine weight (dry): 12,009 lbs.
Overall length: 172 inches
Fan diameter: 110 inches
Thrust at TO: 80,711 lbs.
Thrust during Cruise: 15,917 lbs.
SFC (cruise): 15.66 mg/N-s
GE90
Engine weight (dry): 18,200 lbs.
Overall length: 187 inches
Fan diameter: 123 inches
Thrust at TO: 85,716 lbs.
Thrust during Cruise: 15,432 lbs.
SFC (cruise): 8.30 mg/N-s
Two spool vs Two spool
Airbus A-320 (assumed)
V2500-A1
Engine weight (bare):
Overall length: 126 inches
Fan diameter: 63 inches
Thrust at TO: 24,526 lbs.
Thrust during Cruise: 4762 lbs.
SFC (cruise): 16.29 mg/N-s
Airbus A-340 (assumed)
CFM56-5C2
Engine weight (bare)
Overall length: 103 inches
Fan diameter: 72 inches
Thrust at TO: 30,600 lbs.
Thrust during Cruise: 6786 lbs.
SFC (cruise): 16.06 mg/N-s
Sorry, couldn't find an apples to apples comparison for the CFM vs V2500 but think they are very close to one another on the Airbus A-320.
This data come from a study done at Stanford University looking at fuel consumption on various engines.
Don't shoot the messenger.
Turbine D