Well the problem is, any cav kills any footman through sheer charge. So, in that regard, Lancers are no better, no worse than Hobilars.

Where lancers have an edge is against missile fire (high armour all around so same resistance from front and back, plus armored mounts), and other, non-armor-piercing heavy cav (such as... Hospitalers ).

Against armor piercing heavy cav (gothics, war priests...), high armor and AP nullify each other, and the field is evened. Not sure AP breaks shield, or that shield is taken into account in melee at all for that matter.