I'm inclined to think that the Greeks couldn't win anyways. As said before, Urbans beat Spartans. Not to mention Praetorian Cavalry will eat Greek Cavalry for breakfast. (ouch)
No, they are NOT overpowered. (Play against the Seleucids as the Romans in a 40k match and see what happens
, Catas/Chariots anyone?)
Yes, for infantry factions, YOU ARE SCREWED! Make no mistake, Spartans/Sacred Band, Royal Pikemen, Chosen Swordsmen are good and all, but they WILL LOSE! (Seeing as Spartans cost 1.2k denarii and Urbans only cost 860)
The one exception to this is the Germans. In a forest map, a good player can do alot against the Romans with Germania. (Teutoberg Forest anyone?) Beserkers/Chosen Axemen hold their own against roman infantry as long as they are not whacked by pila. And Screeching Women? A god-send.
If my opponent is Roman, I never go as a phalanx faction. (Germania's warband is a very crude, and weaker version or the phalanx, so I discount it).
Instead, go as a faction that has HAs, CAs, or heavy cav. (Or go as Germania
). HAs/CAs work wonders.