Reduced thrust take off and climb actually uses more fuel, it is strictly for engine life.
On the B777 we used OPT's for take off calc, with a double check from either the opposite side (PM's) OPT or the flight deck lap top. SOP was an independant check, the entry of numbers were spoken by the PM and verified by the PF, and the third pilot (if there was one)on the lap top. On the 744 I make it habit to reference my handy V2 vs weight numbers, compare it to the flight plan and set it initially on the MCP. When the load sheet arrives the numbers are compared as that is where there can be mistakes made (incorrect load sheet data, bad math generally).
Where the pre set on the MCP comes in handy is if a tired piot accidently enters ZFW on the TO weight line on the performance page, pretty much where one can get a 100 ton difference (100 ton sounds like an average long haul fuel). The numbers that the FMC would spit out would then be way off the pre set and the mistake would be obvious, if you get my drift.
Just my way of not doing the same thing as these poor guy's. . . knock wood my friends, smart people have made the same mistake in the past.