I was only able to find this-
Although the efficiency ratings of ductless systems (SEER from 10 to 12) are not as high as the top-of-the-line central air conditioner (SEER up to 16), they can still be more efficient than window, wall and even central units. Since mini splits have no ducts, they avoid the energy losses associated with ductwork of central forced air systems. Duct losses can account for more than 30% of energy consumption for space conditioning, especially if the ducts are in a unconditioned space such as an attic. from
this article (scroll through the page to get to the article.)
As I mentioned before, I like being able to "zone" the house by keeping the temperatures up in the parts of the house we are not using, and down in the parts we are, rather than have the whole house at the same temperature.
LSA (posting on hubby's account.)