I have see them at my LBS with Tune hubs, they are very light and nice, I did consider the set from Extralight but maybe in the future.

Got the Dura ace 7900 levers today please with them 30g lighter than the 7800.
Bike now weights 6423g

WOW! Impressive build! I would love to be able to do such upgrades myself too, but I don't have the skills or tools to make it propperly like you.

A place I see to upgrade could be the crankset? FSA cranks are quite heavy! Zipp 300 cranks on the other hand are really light and can be found really cheap on ebay. When counter calculating the money you can get for the FSA crank, then it will be a really cheap way of saving 100+g.