We are asked regularly about the speed of adjustment of air suspension (full kits) with everyone thinking that faster is better. This may not necessarily be so depending upon the purpose of fitting air to your vehicle.
If you are going to be playing with the air or showing the car (its addictive and great fun) then fast is a good way to go but bear in mind you need a lot of air and additional tanks and compressors are likely going to be required or it will run out of energy pretty quickly.
If you are attracted to air for more practical reasons and just want a low car you can lift to clear obstacles then a slow or medium kit will meet your needs, be cheaper to buy, simpler and more compact to install and can be a great way to go. Many of the most expensive vehicles we fit air systems onto are using the basic controllers not on the basis of cost but for packaging and simplicity reasons.
Fast kits are very tough to get to hit the pressure target, so tough to live with on a daily basis, but there is of course nothing to stop you fitting dual tandem controllers – fast for playtime and slow for drivetime.