Think about this for a minute...
Electricity always goes to the straightest path to ground with the least resistance.
The spark will only shoot to one of those electrodes, regardless of whatever hype blah blah whatever, one of those grounds is closer to the electrode. The little demo things that show this crazy spark are done in open air, the story isn't the same under combustion pressures. It takes more power to shoot a spark under compression, also that spark is shot straight and a lot more directly to the nearest ground.
Which leaves you with pointless grounds on your plugs, and your money in someone else's pocket.
Put shortly, multi-ground spark plugs are a gimick.
Though there are ways of cutting and clocking conventional plugs that will actually gain horsepower, but even those effects aren't felt in any engine under 600-800 horsepower.
NGK or Motorcraft plugs are your best bet.
I've never had a single problem with my NGKs.