Very interesting histories and a stroll down memory lane here. (I did not know of Virtuali's work with ATP's "descendents.") FYI, Dutch - the FS Captain developer - has said the next version aims to implement saving / loading (so you won't lose ((much)) if the simulator crashes) as well as an FCOM that's not an in-sim gauge -- hopefully still an ACARS feel-alike device though.
I believe he's referring to a single "traffic density" setting. VoxATC does not have separate GA and Airliner traffic levels.Then too, VoxATC has a "Max number of AC at an airport" setting, but I don't know if that's exposed via a GUI.