Hey Rom, well I never notice that problem (in such extreme way) using Ngones with Houdini + Karma/3Delgiht/Mantra. So chances are it's also a matter of file format + DCC/Render Engine.
(.FBX is probably better to use to deal with Ngones ?). But you are right that using MoI tris export without that centroid (.ini) option "on" produce very nasty connections that result into odd reflection.