Sillypeoples,
"Typically engines are more fuel efficient when the power is pulled back and you get closer to some efficient L/D".
Incorrect. Jet engines are at their most efficient when operating at highest speed/temperature. Selecting a derated climb thrust for example burns more fuel than going for full climb. However the ratio of engine life cost to fuel cost is what a company has to balance. Terms such as Cost index deal with this for climb crusie and descent. Take off is a different matter with the balance of commercial load against engine wear.
Remember the size of the engine and its larger than required thrust on day to day ops is down to the fact that it has to meet the performance requirements when the other engine stops working over a large atmospheric range !
p.s the B777-2 I fly has a MTOW of 347 tons