Here are some more fuel burn comparisons.
Source:
http://www.boeing.com/commercial/sta...f/777_perf.pdf
B777-200
GE90-77B fuel burn/seat over 3,000 nmi 124.5 kg - 274.5 lb.
Trent 877 fuel burn/seat over 3,000 nmi 127.6 kg - 281.4 lb.
B777-200ER
GE90-94B fuel burn/seat over 6,000 nmi 274.5 kg - 605.3 lb.
Trent 895 fuel burn/seat over 6,000 nmi 283.9 kg - 626.1 lb.
B777-300
GE90-94B fuel burn/seat over 3,000 nmi 118.9 kg - 262.2 lb.
Trent 892 fuel burn/seat over 3,000 nmi 122.2 kg - 269.5 lb.