Epic replaced the strap system (as noted), beefed up the deck lines and bungies. Epic uses Spectra instead of stainless to save weight, a signature factor in their boats. Personally I've paddled Epics for years and love the foot pedals. It is a shame some manufacturers are still making the kind where the whole footpeg moves to steer the rudder.
The articulated rudder had a breather so that the void would not overpressure. Now that there is a drop down skeg in the rudder, the breather is unnecessary. I've never seen an issue with the seat rail coming loose. Fortunately Epic strengthened the connection between the seat and the rail, which used to be a problem but has not existed since the latest models.