We don’t use ABP for air installs, we use the new Solow air.Thanks @The Van Cave
I spoke to Luke at Plush and he offered up the following explanation (just for everyone's info).
All systems will lift and drop as high as each other. All the systems have 3 preset ride heights which you can save to whatever you desire (we usually do a speed bump/off road height, everyday driving height and a lowered cruising height)
System 1 is a pressure based system so although you get presets as explained above, pressure changes with temperature and load, therefore, giving you an accuracy threshold on a vehicle this size of about 15-20mm when scrolling between presets.
This is where system 2 and 3 see the advantages. They are both height based systems and the presets are not effected by temperature or load. Again the main differences between systems 2 and 3 are different interfaces. The touchpad on system 3 is a little more user friendly with bigger buttons. It also has active load levelling so it will monitor itself every 45 seconds and will adjust its height accordingly which system 2 does not. This meaning if you were to load the van in system 2 when the additional weight is added or removed you would need to press the preset command button again to accurately adjust itself to the desired height whereas system 3 does all of this for you automatically.
All systems come with a Bluetooth app to control the vehicle from your smart phone.
Mostly accurate information about the management systems, but he hasn’t confirmed if their bags will tolerate a 750kg load in the rear.