I didn't know that - when I bought the C4 picasso the salesman just said that the EGS box had been renamed.The EAT6 is a conventional automatic transmission with epicyclic gears and torque converter. It has clutches to lock and unlock the various ratios, just as the 4HP20 and all other electronically controlled automatic transmssions of the last 20 years.
It is not an electronically controlled manual transmission.
I think the "Sensodrive" box fitted in the Pluriel was the first one Citroën used and was a problem right from the start, I assume it was not the same system (EGS) as fitted in the first C4s.
Maurice