Well, i am not a specialist in history, however i think the agoge wasonly to spartan citizens.
The "Perioikoi Hoplites " were not Spartan citizens, so tech shouldn't affect all Hoplites, only Spartiates.
Decreases the cost of tech as it no longer affects hoplite citizens.
EDIT: Spartan champion are supposed to be the strongest infantry in the game (spearman). Macedonian Champion Silver Shields are equivalent and without the training time penalty acquired with "agoge" tech. See also D2867 D2868.
Patch decrease cost from 500 food 500 metal to 500 food 200 metal (cheaper than "silver shields" tech).