As the power of central vacs has increased, and the cost has decreased compared to high-end vacs, I have become more interested in them as a viable alternative to portable vacuums. They are referred to as 'ducted' vacs elsewhere in the world, and I found one called vario-vac that has unique tubing that is flexible. At first I thought it was just larger diameter corrugated hose, but it is a more flexible form of the pvc tubing.

Since I do not care for emptying a bagless vac, I would prefer some kind of disposable bag or liner. 

MD used to offer a hose that was 20 ft with a 15 ft extension, which I thought was brilliant, but apparently it did not work out. Hose storage systems still require dealing with a long hose when fully extended. I would think a shorter hose and more inlets would be the way to go, along with maximizing things like the Vroom, Spot, and Wally flex. Instant clean up of the mess as it occurs. 

In a home with wall-to wall carpet say, only in the bedrooms, or only low pile carpet, a turbo brush, or straight suction tool should suffice. Very few of the systems offered outside of North America even offer electric power nozzles. Nearly all new construction in Canada is pre-plumbed for central vac.  What do they know that we don't?

they offer a RFC unit that eliminates the need for even low voltage wiring.

First, design the system around a 25 ft hose. (about the length of a cord) absolutely no more than 30 feet. That five feet makes a HUGE difference.

Second, do not skimp on the inlets. You should be able to clean up or down a staircase, and around a bed w/o piling the hose on top across it.

Third, hold the hose in a couple of loops and drop it as you work away from the inlet, and pick it up as you work back toward it.

It's different, but it it not difficult to do. Even a straight suction rug tool on a c/v does a good cleaning job, unless you are on thicker wall-to-wall carpet.

I do not know what kind of warranty comes with the house but the builder should have compelled the sub who did the install to correct the situation and add more inlets.  I cringe when someone walks in and says "My house was pre-plumbed for a central vac" 

is paramount when installing a central vac.  The full array of spot, vroom, wally vac, sweep inlets makes a huge difference. No one ever complains after a proper install is complete.  The cost is forgotten as the tiny messes of living are swirled away in seconds by the constant indefatigable suction.

only solves the storage problem, it exacerbates the long hose in use because it uses a longer hose. The hose storage inlets are VERY expensive. It would take longer to store a 50 ft hose in the wall, and get another 50 ft out of the wall, than it would to just unplug and re-plug a 25 or 30 ft hose.  Correct hose handling technique will eliminate the wall scratching. I'd rather handle a 30 ft hose than lug a vacuum with the cord.

Too often the C/V is installed by another craftsman, who might be very competent in his field, but knows nothing about vacuums.

I think, unless the open space is too far for a 25 ft hose to reach, that should be the length around which the system is laid out.  In the newest hoses, 25 ft is rather light, even with an electric coil.

I repaired a Turbo Cat for a customer who also purchased a Stealth kit. I tested the T/C on a Miele S4 Neptune, and it really screamed, even on the plush (thick, but medium height).  More inlets are better. Shorter hoses are better. Unfortunately, my home is 127 yrs old. Balloon construction, plaster and lath, 1& 1/2 storey.  My dream house has a central vac.  I like the quietness, the tremendous suction and airflow, and the total removal of all particles from the living area.