I’ve found another difference between V5 and V6 with regard to the AddText method. It seems that V6 is ignoring \n for line feeds. Please try this example in both and you will see the difference:
import rhinoscriptsyntax as rs
textstring = "Hello\nWorld"
point = rs.GetPoint("Select a spot")
if point:
rs.AddText(textstring, point, 4, "Arial", 0 , 0)