ice usually means either your air handler isn't pushing enough air across the coil, or your system is out of refrigerant.
so first step is to set the cool/off switch to off. then set your fan switch to on. if the air handler fan does not turn on, then you have a problem with your air handler or thermostat. possibly cheap. possibly something you can fix yourself.
otherwise, you probably have a problem with refrigerant (which should not deplete, and if it does then you have a leak somewhere) or your compressor. in either case, you should leave your system off to avoid damaging your compressor until someone can come out and look at it.
Rather than focussing on how it's done (inverter drive) focus on what it does (variable speed compressor)
Essentially, the variable speed allows the compressor speed to match the cooling load, so rather than a fixed speed compressor starting, cooling, stopping, starting, cooling, stopping a variable speed model can simply adjust its speed to match the cooling load, while running continuously (until there is no cooling load, or one below the minimum speed it can run efficiently, anyway.)
That has several potential benefits - one is that starting the compressor motor takes considerably more power than running it - so many starts and stops add up - this (alone) might be what someone who says "they only save power over 8 hours or more" is speaking of. However, I think any such statement is far too general to pay much attention to, given the variations in individual units (I've been considering mini-split heat pumps, and have read a lot of data sheets - some are surprisingly different even for closely related models made by the same factory...)
Additional benefits are that rather than the system blowing air that's cold, and then stopping, it blows air that's cool, all the time. Among other things, this improves dehumidification performance and is also usually more comfortable.
You state that you use your air conditioning less than 8 hours per day - but how many days a year? It is true that if the initial cost of something you use rarely is much higher then the payback for any more efficiency (from a unit costing more) is very long (and may exceed the useful life of the product, in some cases.) However, that is not something that is amenable to analysis from afar, and will vary with the initial cost, the energy cost, the use, the climate...
If your cooling needs are limited, and the cost differential is high, just look for the best efficiency among the lower cost type units, and don't worry too much about "the future of HVAC" if having it does not make personal economic sense for you. Something better may be invented before this air conditioner wears out...
Of course, if you are buying 9 of the things, you should at least consider a central system. But that may not pay off in a reasonable time, either.
Best Answer
Annual maintenance is recommended by the manufacturers, and installers of the systems. The majority of the maintenance time, will be spent on cleaning the unit. Keeping the unit clean will help keep it running more efficiently, and can increase the life of the unit.
The technician will inspect the unit to insure it's still in good condition, and will look for parts that may be near the end of their life. Replacing parts before they fail, can save you the headache of replacing them when they fail (which will surely be on the hottest day of the year). Replacing part before they fail, can also help prevent damage to other parts of the unit.
Depending on which company does the service, they may actually measure the amount of cooling the system is providing. They may also check for refrigerant leaks in the system, but likely only if the refrigerant level is low. If you have any questions or concerns, they'll likely address those at this time.
While these units can run trouble free for many years without maintenance. Keeping them clean and in good repair, can save you money and reduce the chances of a failure. Of course you can do some of the work yourself, but often it's easier to pay somebody else to do it.