There is too much made of the point of balance thing, why limit your reach? It is sometimes neccessary to shorten or lengthen your grip to avoid putting yourself within your enemy's reach. The modern term is pool cue-ing someone, where you shoot your polearm forwards like a pool shot.

Lindy Beige does a number of YouTube vids that show a fairly flexible use of shafted weapons 9& swords, too).

BTW if you haven't seen his large number of videos, they're always good value.