Well, the theory of how they work is what is used in the "Hospital Quality" Honeywell Electronic Air Filters that I had installed in my home in Ontario, California, years ago...I cleaned out the plates and wires about three times a year, and got POUNDS of soot, and little fibers out of it every time, and it took the smell of the smog out of the air in the house...it also cleaned up any cooking smells faster than anything...It sure made breathing easier when the smog was so bad that you couldn't see to the end of the block.
I know that the Sharper Image is WAAAY overpriced, so I recently bought an Electrostatic Cleaner and UV (with a fan) unit (brandname: LumiPure) from COSTCO, and it was only about $150...it processes the air with a high-output UV tube also, claims to sanitize the air, kill dust mites, and make your tires stay inflated...
Maybe it is the electromotive force required by the SI unit that makes it produce more Ozone...the LumiPure makes some Ozone (I am familiar with the smell from my exciting boyhood) but it is not objectionable to me...the wife likes to use the unit while we are out of the house...it has a timer for just that purpose. It does gather a lot of schtuff on its plates...
I'm a believer....