After mucking around with modern plugs for a couple of years, I've had the same set of Champion X's in my car since 2006. Initially, I used adapters to run a variety of modern plugs, because they had a much bigger heat range. I spent a whole lot of cash on various modern plugs and eventually found that with the original Champion X, the car started easier and idled smoother. Also, being a pull apart, and therefore serviceable, plug, you only pay the bigger price once.
Cheers,
Rob