I had a similar thread going about a month back and a lot of people dissuaded me from doing it quoting nightmares of maintenance and leaking diaphragms. I'm still tempted. The idea intrigues me and remember the FWD 6G actually had ECS which used air struts. Of course after 20 years most of the systems have failed and a lack of spare parts means most people ripped it out. But let's be honest how many Galants are running on their original springs and oil filled struts?
As long as the compressor, hoses and electrics are up to par, I would think an air shock posed less of a maintenance issue as you can replace the diaphragm easier than rebuilding a shock. The real problem for me is the one quoted above. I'm not sure I can justify spending more than the entire car is worth on new suspension. If I was sure it would last 100,000 miles as some air suspension manufacturers claim I'd be tempted but my experience with KSport in the past hasn't led me to believe that they command that level of reliability. Not insanely bad by any means but for $4000-USD you can get Ohlins, DMS, Hotbits, pretty much anything in fact! You could get a set of EVO Bilsteins, aftermarket springs and have the whole setup revalved and about half of that left over.
Bottom line if the ride was Lexus plush on soft and could be firmed up to handle track abuse I'd be all ears. If the ride quality and performance is just 'okay' however I'm not sure it justifies the price. If you want to do it though, I'd love to see you pull it off and I anxiously await your review on the ride plus pictures of how it sits. I could be convinced if someone could show me it is worth doing. I am truly dissatisfied with my current setup and I really do want to find something more comfortable.