I have also hab some problems with the obj exporter. I agree that the only way to get a decent usable .obj is if its quadrangulated. but only as a post process before the obj is written. I for one prefer to do the quadrangilation myself as xsi does the best automated quadrangulation i've seen.
So an option in the export process to keep as is or quadrangulate will be great. ...after all your object gets triangulated at rendertime anyway.

An obj file will suppport ngons with holes in it as long as thee are two edges or a quad holding the hole

one thing i've noticed is that fillets with very small radii are not converted acurately. maybe something to do with tolerance being too high for the tesselation process?