As captain my role with regards to navigation is mostly supervisory, when I do take the conn it’s mostly eyeball.
Having said that I do think that, for me at least, using ECDIS is a significant gain in situational awareness.
I really notice the difference working with ECDIS and then doing a relief job without. Without, after a bit you get used to having to make greater effort for less gain and settle for a less complete picture. For example approaching a crowed anchorage with ECDIS I can quickly pick out a good spot, without I could of course get a fix then take a bearing and range to the anchored ships and plot each one, but it’s not worth the time and effort. Better to watch ahead than bent over the chart table that long.
As far as the mates go, I require plotting manual fixes (from the radar) on the ECIDS so the argument that there is no cross-check to the GPS is not valid. In fact it was worse with paper charts because 99% of the time the mates were just plotting GPS fixes on the paper chart anyway.