I get that and I don't worry about an average ATF visit. I tend to think of these things in a worst case scenario situation - usually, from the standpoint of being investigated in the event that I actually have to use one of my guns in self-defense. We all know Mass will crawl up your ass trying to find something wrong with the fact that you defended yourself, so it's not a stretch to imagine a scenario where the BATFE would do the same.
And yes, I know I am way way over thinking this, but I do think it's a shame how convoluted and difficult to understand these laws are. Trying to do the legal thing is almost impossible because nobody is ever really sure what the hell the laws mean for certain.
In the end, I'll just throw things in the book that I buy that are around 50 years old, but I'd feel better having a clear set of guidelines.