Surely you folks will remember the splitfire spark plugs that came out sometime in the 90's-- they made all these claims about how great your engine will run with these plugs, were heavily advertised on TV, magazines, etc. I found them on closeout at Rockauto for about a buck a piece.
They were run in my '04 Honda Odyssey 3.5L V6 for about 36k, the interval I usually run copper plugs for. Before putting in these plugs, I had the engine out of the van for a rebuild-- I did everything but the bottom end. New seals/gaskets, cylinder heads went to machine shop for a valve job, new seals and milled the head. Reason was that the PO overheated the thing and blew a headgasket. Compression was good so I left the pistons/rings/bearings (the entire bottom end) alone. Van has run great since, no issues.
Plugs look to have normal wear for 36k miles. Color was a nice grey/tan-- a tad bit of deposit accumulation, but otherwise a clean plug. My conclusion is that the split-fire design is pure marketing hype, as the center electrode wore down primarily in one location (the rear, toward the outside electrode) on all plugs. That seems to go against the marketing which suggests the split ground electrode promotes multiple spark paths. There is zero evidence that the design allows the plug to last longer, as these are well used up and definitely due for replacement.
I once helped a buddy change plugs on his Jeep Commander that was misfiring. He ran copper plugs over 100k, and at that point the center electrode was worn down below the ceramic insulator, but many were still firing in that condition. So surely I could have run these longer, however the center electrodes were extremely rounded off and the gap had widened significantly from the 0.044 they were originally set at.
I have six more new ones that I'll be putting back in. Not a bad plug, but similar performance to an Autolite or other cheap copper plug, in my opinion. The only good thing worth noting is that they're made in the USA. Someone correct me if I'm wrong, but I don't think they're made any longer. I don't mind running coppers in this engine; they are super easy to change for a transverse engine-- literally a 5 minute job.