A student of mine asked me once, if I was so interested in Japanese comics, why my drawing didn't look much like manga. The short answer I gave him was that "I'm not Japanese," but the long answer is a little more complex.
First of all, as the "Vourasq War" excerpts from this comic surely demonstrate, I'm not very good at the stereotypical manga style. This is because I discovered Japanese comics relatively late- by that point I was already well on my way to developing my own personal drawing style. Secondly, there are a number of things that stereotypical manga deliberately chooses not to do well- such as letting you know the race of the characters- that I feel are important for the type of stories I tell. Finally, as much as I like the whole big-eye, giant-sweat-drop, spikey-hair thing, manga really shines in its more invisible elements such as subjective motion, pacing, collage, emotional content, subject matter, and composition. These are the things I am most keen to incorporate into my own work.
The medium-sized answer is: I want my work to gradually become more Japanese, but from the inside out, not the outside in. Constance, I am sure, would have a few harsh words for any attempt I made to wear manga as a skin over an un-Japanese heart.