Not to poo poo on this but when WG DGPS is only $10 more why not go with the "better" sealant. I understand M37 products are more value lined for production detailing and such but a sealant isn't something one needs gallons upon gallons of.
Perhaps only $10 less, but overall most products in the line are less expensive when compared to their wolfgang equivalents. The product line fits a nice niche where it's better than what I can buy at the local auto parts store, yet doesn't break the bank. I have two daily drivers that aren't collectors. I want them to be clean, protected, and look good. So far the McKees line has met or exceeded my expectations.
Considering how many pros here who do many cars a week use it, I'd say they like the price point too.