I've profiled my 3800 with my new Colormunki and the printed colors are spot on. Yet the nozzle head check indicates about 1/3rd of the magenta nozzle is clogged. (I've tried both the power cleaning and the windex methods but no luck.) How accurate is the nozzle check? And should I just consider myself lucky and not worry about it?
If you print a solid block of magenta you will definitely see banding. In normal photographs you might see some banding in areas where magenta ink is called for.
I also have a 3800 that has some problems with the magenta channel. It started with just one bar missing in a nozzle check and over time it now has a few more bars missing. All my other colors are fine. My attempts at cleaning and Windex have also not worked. Overall though, I really can't complain as I have been using the printer heavily for about 5 years and have certainly gotten my moneys worth out of it.