At FMM both E-50 and E-60 were functional models; the E-50 was played in public demos by a talented musician and some units were present in the 'hands on' zone.
I think that E-50/60 are 'light' versions of E-80, for users that are looking for an easy-to-carry arranger with nice sounds and features, and that accept to renounce the impressive on board amplification and features of E-80 because of its size and weight.