akerosid,
you said that the A350 would be playing catch up with the B7E7. The B7E7 is actually playing catch up with the very successfull A332 which all but ended the B767.
The A332 is quite close to the performance of the proposed B7E7 and considering Boeing are using many new technologies which haven't even been part of R&D programmes, you have to question whether the final product will be as light and as 'efficient' as it's currently being sold as.