I don't doubt that at all. I plot and do all the contours by hand for every storm. I don't have software to feed in a bunch of data and auto generate a snowfall map from averaged/smoothed data. A lot of the NESIS maps are conservative and in some cases way too conservative like February 2013 where there is no 30"+ area over CT despite a very large area and many many reports of 30-40". @ORH_wxman can attest to that, we were talking about that a few weeks ago. That's just one example.
So i knew the NESIS map would be a bit lower/conservative, every map is going to look a bit different. However even with that being said there are some glaringly obvious problems with the current storm. There is a small area of 4-10" near Danbury which i am certain was well over 10" being on the eastern edge of that deformation band. Most of the reports around there are 17-22" and on the low end 12-15" so there's no reason why a hole of sub 10" should be there. Just one example. The area of 20-30" should also be much wider over NJ west and south of NYC, even with smoothing considered, many reports of 20-30" in Monmouth and Ocean counties away from the immediate shore.