Well, to be fair some of the technology is transferable, for instance, on the sonic cruiser it would be critical to have a wing of reduced thickness:chord ratio. Therefore alot of work would have had to go into better wing structures (be they composite spars or whatever).

That work can also make for a thinner wing for the 787, improving the drag levels of that wing as well.

Infact a lot of the stuff , the barrels as i mentioned were also taken into the 7e7 , they had to reduce weight and make the aircraft very eff. to match its predecesors economy even at the higher speed. Also the electrical systems were first conceptualised with the 20xx and sonic cruiser projects before being passed on to the yellowtone research team. But most of the higher end work was done by bair’s team and the suppliers in the global partners , and hats off to them , being a part of the 7e7 and 787 from the start i can tell you that the ammount of challenges that boeing had to overcome were mind bogeling . While we only had info on production and supply lines but even then the production process , integration , working with the partners , improving each other , finding bottlenecks and dealing with them and recource allocations were all perfecly executed ( so far so good) and hats of to them for that . Having personally been involved with boeing ( ID , and BCA) i can tell you that boeing can sometimes be a very hard company to deal with specially the defence side of the company but it seems that the 787 has been blessed by the gods .