I did my exam in a DA42 about a year ago and I think it depends on the person whether or not its easier to use. Its true that the multifunction display with its huge map makes it a lot easier, which is why we usually flew in the backup mode (the primary flight display on both screens, no map). My instructor had even found a way to do partial panel on the garmin 1000; he would stick a little piece op paper on PFD over the DG.
Regarding the scanning; you do have to develop a scan in the twinstar and its still according to the basic T but its not the same as in a plane with conventional instruments. I would recommend also using a sim with a conventional setup as I believe its still important having experience with this type of cockpit.
And just for the record, I had no trouble flying a kingair with a conventional setup after flying the twinstar
