I bought 5 or 6 N3C Champions about 11 years ago when I had a plug fouling problem because the autoparts store was around the corner and they were about 1/2 the price of the bike shop, 10 miles away. There is not a dimes worth of difference between a Champion and an NGK. Most problems are due to improper cross referencing, and they dont match exactly. (The N3C is like halfway between a B7ES and a B8ES. Thats not what the book says. Its a conclusion I came to.) Of those Champions I bought, I still use 2 two of them. They have been cleaned and recleaned (blasted) countless times. The other ones were lost on the trails over the years. I just threw one away, because the wrench angles had been rounded off from improper tools on an emergency trail repair.
I use them interchageably, and cant tell the difference without reading the label.