He is playing as Rome, would you exchange 6-8 Pedites Extraordinarii, Triarii and Principes for one unit of Eles? I would not, when I want to scare enemies I get some Gallic Mercs at a much lower price and add some flaming arrows.

Now I cannot actually recall the prices as I am not even playing as Rome right now but Baktria (sacriledge!! I know), but I seem to recall that the ratio I gave is close, but even four P E is worth more than one Ele IMO.

As Baktrian I like them though and try to keep an Armoured Indian One in each main army when I can afford it and the barracks for it are ready.