Sorry I forgott about...
I was just in Athen and there are no DMU class 621 there. The are only operate from Thessaloniki to Florina.
In / around Athen quite every Local Train are operated by 460 Desiro. Every Track arround Athen are Electrified.
I saw an 560 Stadler GTW far away in the Larissa Station and dont know where the operate on because there is no reason to use Diesel instead of the Desiro.
In the Desiro the toilet is clean but the water tap was missing! There is no way to wash your Hand!
Between Doukissis Plakentias and the Airport the Subway use the same Tracks as the TrainOSE Trains.