Well I cant speak for ^that device, but my dad is an authorized dealer for The Rusterminator, and lets just say this. On an old beater car he had, a 1991 crown vic cop car, he installed the rusterminator. After something like 6 years of HARSH NY salty winters, there was minimal surface rust on the new exhaust, and the already-present rust holes were no bigger or weaker.
On his 2002 impala cop car, which has ALSO seen raggedy, salty NY winters has ZERO rust on it w/ the rusterminator.
Rusterminator actually guarantees your car w/ a new paint job that it wont rust thru (car has to be like a max of 5years old or something..)
And some more food for though; the US Navy uses a GARGANTUAN electronic rust disruptor on all their naval ships.