A hypothesis concerning -ite: whereas -er belongs to anyone using a Germanic derivative, and -an belongs to anyone influenced by papistry (as a practicing R.C., I jest; basically any western European and their historic colonies), the greek derived -ite belongs only to the greek studying elites, and the resentment thereof imbues the suffix.
Actually, the weirdest of those seems to be Netherlands with "Dutch", which is horribly confusing to anyone not fully aware of the distinction between the Netherlands and Germany (Deutschland -- which to English speakers sounds dangerously close to "Dutchland").
