hp increase is optional. 300 something hp is miniscule, and the points can be used to maximize your damage, you wouldnt need that 300+ hp if you killed it before it hit you for that much now would you?
and yes, set effects play a big role in your build. why would i need mp recovery when i already get 14 mp recovery from set effects. same goes with increase, when the SAME set gives me more mp than increase will. oh hey look, 16 points that i can use to get more attacks, to do my job more efficiently.
and since i have 2.8k hp without hp increase (3.1k with), that hp amount is hardly going to make a difference in places that will kill you regardless. the chances of that amount of hp making a difference between staying alive and dying gets drastically lower....
prefer anything else all you want, but efficiency is the key, and that's whats been the most efficient by not only myself, but by a lot of other yukis that know what they're doing to maximize their potential.
a suggestion for this guide: back up your information and state facts behind your reasonings, like i just did. this "ultimate" guide coming from a "master" of yukis, needs a whole lot of work, in my opinion.