I suggested an option to avoid pax walking through the fuselage (by letting them disappear before entering the airplane), so I hope that eventually GSX will be great to use with smaller airplanes. I did that in P3D and it worked OK, at least for airplanes like a KingAir.
Having said that, there is still a problem with the aircraft configuration editor right now. Umberto wrote in another thread that it is recommended to use GSX only with officially supported airplanes until the issue is fixed. Hence, small airplanes are currently not supported.