I went 2rogue to cover all trapsmithing skills, Umd, and stealth.
If going ninja spy you already have dodge, making tempest require 2 feats for +4 to hit when moving, +2 shield AC when twf, and ~5% dps. 6Ranger already gives twf/itwf/rapid shot/manyshot/diehard, rams might, early healing wand access, and some favored enemy damage.
If going handwraps, pure Monk is better. I wanted to use shortswords, specifically radience II, so 6Ranger fit well. Since I also wanted Drow, and Scorpion Wraith counts as a Rogue PrE, I chose against 13monk/7rogue or 13rogue/7monk. I believe Drow will overtake halfling and WF on damage when the PrE is released, emphasis on when...