I am not sure if there was a point to be made. If there was a point to be made I am probably not the one to make it.
Basically what I did was I ran the mercruiser filter through the warranty period(so there would be no excuss for the manufacture if there happened to be a problem). Then when that period was over I went with the Napa for a couple reasons: first Napa gold filters are good filters. Second, my napa store is closer than the one hour drive to the marine store. I am not saying that mercruiser filter is better or worse than the Napa. I did not take apart any of the filters to inspect their quality. For all I know they could be made under the same roof.
Duane, you are correct spend the extra dollar for quality oil and filters. cheers