Quite a few Missouri wineries blend something into their Norton. It's a high acid wine, like chambourcin, so something to cut that is typically used. As for the taste, I'm not sure I would ever compare it to a Merlot. Many MO winemakers I have met compare it to a cab sav. That's not quite right either, but it is a very big wine, like cab, and unlike merlot. It often has the spice that you see in a lot of syrahs, but that can very widely even just here in MO, depending on where the grapes came from, the yeast used, etc. A little winery in Hermann produces 2 nortons - 1 produced in American oak fermented with a syrah yeast and the other produced in French oak with a typical norton yeast. Massive difference. Two completely different wines.
Quite a lot are produced wrong (in my opinion) and have left the acid alone, producing a harsh wine that convinces most that try it that they hate Norton. The acid needs to be worked, but I would never add water to do so - I'd chemically reduce it or blend with a lower acid wine after fermentation. Very interesting grape!