Have you actually weighed the fully built up bike yet? we have all done the 'adding of individual items up' to get a really low weight only to find the actual fully built weight weighs more. I have a litespeed ti build, with xtr, deus, flite ti, carbon ridgid pace forks etc that weighs an honest fully built weight of 21 lb. Your build even manages to fit on Manitou Mars forks and still weigh 2lb less!
Nope, not weighed it altogether just yet (not quite fully built) - though I have quite meticulously weighed every single item myself to the nearest gram (no using mfr stated weights or estimates from weight weenies) including all bolts/cables/etc, so I can't see it being more than 50g out either way. But sure, I take your point, will have to do this once complete!
Would like to see details of the Litespeed build. When you look at the weights carefully the top-end stuff is not always the absolute lightest. I assume the Litespeed frame is heavier than this for example, also Flite Ti's are aren't especially light, Pace carbons are a couple of hundred grams heavier than the Trigon equivalent. XTR depends on the year and the parts - as an example the M752 chainset on this build is lighter than all the XTR equivalents.
I've really carefully checked out every single part on this build to make sure there's nothing (leaving aside the super-expensive) that's a worthwhile weight saving over what I've got, though there are still a few grams that could go here and there. And I'm interested in hearing suggestions in case anyone has any!
What makes the biggest difference is the wheelset - those Crossmaxes are a good 300g lighter overall than many other lightweight wheelsets, and add to that the pair Kenda Klimaxes saving of 200-300g over other lightweight tyres and it starts to add up...