I ran a test awhile ago 5 battles with all of the "elite" Phalanxes. At the time I had not correctly modded Royal Pikemen to have the longpike that they should have.

I forget the exact results but, it basically went like this.

Silver Shields 5 - Royal Pikes 0
Silver Shields 4 - Spartans 1 (Silver Shields shuffled their way to be facing away from the Spartans)
You can guess how other battles would have gone, being that these are the 3 best phalanx units in the game.

In general the long pike Phalanxes dominated everything else because the shorter spear equiped units were completely unable to close the distance, and if they tried they got mauled even harder.