i have no experience with air bag suspension but i do with lowered coils, and i can say that the ride quality will be more dependant on the spring manafacturer than how low the car is ( excluding cars riding on there bump stops)

my experience as stated earlier is that eibach lowered springs have dramatically improved the quality of my cars ride, replacing the front struts has been the icing on the cake.

for me it has turned a hard ridding car into a comfortable ride that now also handles far better than stock.

so in my view its not the lowering that causes trouble or causes the car to be unsafe, its how its done.