Really, there are not many improvements to our engines that cost so little and do so much. Put aside the fuel economy and easier engine start, the advantage of maintenance-free spark plugs alone is worth the money. These spark plugs will probably outlast most engines.
All my friends got these now. Plain and simple, changing spark plugs is now a thing of the past. Get the iridiums in and forget about it.
About the fuel economy, not much improvement here. Engine starts are better, easier, cold or hot. Tried these in my Kawasaki VN1500D and Suzuki DR350.