The 20S EVO was designed with a fixed type, shark fin antenna as opposed to the flip up antenna of the original 20S. This sleek antenna design improved group Bluetooth intercom stability and distance, while updates to the hardware allow for a more robust general performance.
Easy to install (on my Arai Tour X4 skid lid) and to use.
Good battery life.
As well as speakers, it also allows one to plug in some ear bud headphones (via a 3.5mm jack) built into the unit.
The in-built radio is a handy feature as is the ability to simultaneously link the unit to ones phone and a GPS..