With protection against rust, premature ageing, road salt, brake dust, dirt and added hydrophobic properties, ceramic coatings providea host of benefits. You don't need to have it done by a professional every month, and with 4 maintenance per year (2 of them in winter) it should keep the coating performing and the car looking great. I haven't really seen any direct comparisons between the most popular coatings recommended here, just people saying they use this or that. Gtechniq C2 works well as a sacrificial coating that can be layered on top of your other coatings, just use it as a drying aid after every wash and you will be building up a thicker layer each time which is supposed to last up to 6-8 months.
So what can you ceramic coat with Armor Shield IX? Here's an awesome video that explains all those things you never thought could be coated. While I'd be totally cool promoting a customer who did such a thing, it's something that the average daily driver or consumer is going to do - especially since most modern cars have coated metal suspension parts. You may do a coating in the future, perhaps when you have a new car in a couple of years and you really want to get it right from the start and protect it as well as possible. While there are several preventative measures applied at the factory, and several aftermarket products that can help reduce rust build-up, one of the most effective products to prevent the mixing of these two dance partners is a ceramic coating - such as Armor Shield IX.
The cost of a DIY ceramic coating, vehicle preparation time and application are far less expensive than repairing rust damage. Nano ceramic coatings such as Armor Shield IX use nanotechnology to seal those tiny pores and valleys in a porous surface like a clear coating. When there is excess humidity, the moisture in the air is sufficient to provide the electrolytic component - which is why cars in very humid climates can generate rust (even when protected by a car cover). Ceramic coat this spring, apply a topper in late summer (August), early November, early January, and then early spring.
This is an undercoating or spray coating that provides a protective layer over metals and prevents water from penetrating the metal (sound familiar).