Hi iacdxb,
You could benefit either way. There is no general yes or no.
N-Gons during the modeling process allow for a great deal of flexibility. It depends highly on your target or what the next step will be. Do I have a rule of thumb, not really, but a feeling or intuition, or sometimes it is just logic. Hard to tell in other words.
What I can tell is, that I like to have a flow of polygons, and preferably quads (four point polygons) on the end. If I leave it to the tool to divide the result into quads or triangles (three point polygons) I will be somewhat forced from time to time to do cleaning up work: sorting the otherwise N-Gone with, e.g., 13 points in a different way.
The application will turn everything during render-time anyway in triangles, so why bother, will someone tell you. If there is no animation then it might be OK. Not OK, even without animation, if the results are long spiky triangles. ...and again, perhaps it renders out fine and no problem might occur.
If animation is given, the way a quad could be bend is dependent on many influences. If the quad was already triangulated—it might be have the diagonal (thinking of the original quad, in the opposite direction.
I could continue here with simple cases and examples. But on the end, as I say it often, modeling is like chess: think several steps ahead to get a good outcome.
OK, let me try a rule of thumb here, whatever creates a mesh on the end with the nicest flow of equal sided quads (squares) will be preferable. How to get there is mostly based on manual work, and not on random decisions of the application. So, the N-Gon might win. But there are certainly a lot of cases where it could be a clever idea to leave it off.
I know there is no clear answer, hence the long answer. I tried to fill in what I got, since we have N-Gons at all. There is certainly more… ;o)
Have a nice weekend
Sassi
