I think there is lesser difference between a 3 and a 4 then there is between a 2 and a 3. Three through 5 are similar positions really and the difference is only in calibre/seniority with the former taking priority. The 6 position is also similar but at point you start batting with the lower order and tail and thus he should be more of a finisher, even in Tests.
Cricket cannot live with the mistaken belief that people want to see big hits. People like to see goals, but no one is talking of moving the goalposts a metre wider either side. (Harsha Bhogle)