Flight Spoilers on the GEX are used the same as any other Jet Aircraft.
An example would be when in the decent given a speed and height restriction, the flight spoilers would assist in decending at a higher rate and also ensuring the speed is kept to the restriction.
The Flight Spoilers on the ground become Ground spoilers, after landing if the Ground spoilers are selected to 'Auto' all the spoilers on the wing will aide in slowing the aircraft.
Hope that helps...
ADG