Modern tests have proven that as incorrect. In an old Ancient Warfare magazine is an article about the Sassanian Noble Cavalry, wherein Heliodorus is cited, but commented as not correct. The author, Patryk Skupniewicz, is very versed in that history and kind of Eastern mounted warfare.
I doubt, that the main strategy of heavy lancer cavalry was to rely on the impact of their charge. If they were up to fight infantry, they would rather rode around the enemy formation probing for weak spots, take advantage of their mobility to attack suddenly flanks or rear.
In melee battles the knights pushed the kontos against the enemy footsoldier, as experiments show that is a great impact to bear (high position at the horse`s back and the up-to down lance push by a highly trained knight might impale two people at once).
The main task for the heavy lancer cavalry was to protect the horse archers against enemy heavy lancer cavalry and when the arrow storm of the horse archers disrupted the enemy formation to take advantage of the disordered ranks and attack so that the ranks got fatally split up.
The Sassanian called their clibinarii
Asavaran.
Not exactly. "Grivpan" was an old form of armored neck protection (the Achaemenid heavy cavalry wore it) and the warriors wearing that were called "Grivpanvar", what the Greek made to "Grivpanvarios". You may see a certain similarity to "Clibanarios", what IMHO was a slang by Western troops taunting the enemy inside their "hot" gear
