We've got quite the dilemma in our gaming group regarding this rule. We know it's compulsory for unit champs, but some of us argue that it is optional for characters (both the 2+ and the 4+ LOS). For the 2+ LOS, the rulebook says that it is permitted. For the 4+ LOS it states that it may make a dice roll. On both cases it is not clear whether you are obliged to take the LOS roll or if you are not.
What do you people think??