Definitely a build to surprise the **** out of the enemy carries. My games have gotten to Sanguine Blade and by that point we have won. This is not a cap guide necessarily, but more of a duel/assault/hold type of build. You can 2v1 easily with this as long as you don't switch targets. Lifesteal with crits is win, and sanguine blade scales with Xin's specialty, attack speed.
I don't like flash in Dominion, I prefer Ghost. I like Dodge seals, if you go with Ninja Tabi. MR/lvl seals are good for Dominion carries. I see no reason to level Xin's Q ability last, should be first.
These "I" sentences don't really matter though, builds are a framework. Your framework rolls faces.