difference between 4.7 version,ecc5.0 & ecc6.0 version with respect to PM.

Hi PM experts,

Can anybody please tell what is the difference between SAP 4.7, ECC5.0 & ECC6.0 version with respect to PM module? What client will get benefit in terms of PM module if they go for upgradation from 4.7 to ecc5.0 or from ecc5.0 to ecc6.0 version?

thanks in advance.

rgds

rajib