The guide is good and I think following it will lead to a significant advantage but only so long as the nation expands. Some builds can benefit from sitting tight, but certainly not this one. The must expand builds suffer a diplomatic penalty b/c many times they'll face allied opposition. Of course it all depends on game settings: score graphs on/off, diplo on/off, map size etc.
I read you're considering doing a Yomi guide. Yommi
I was breaking my head how to play this nation right (as in efficiently) and the best I came up with is going with the nation power, the Dai Onis. I can wait to read your angle on this.