My Versapack 22 barrel is drilled and tapped, but did not come with scope rail.
I think there may be a mistake in the weights listed. You've got the Rossi at 1/2lb heavier in 22 configuration, but a full pound lighter in shotgun with the same length barrels. That doesn't seem right. I'm willin to bet that both guns are going to way pretty close to the same to the point that its a moot point. The listed weights for the NEF's tend to be a bit heavier than actual in my experience anyway.
Anyway, it sounds as if you have already made up your mind, so go with what you feel is the best deal.
I think what we're all saying is that the NEF's may be of a bit better quality. I own 8 of their guns and not a single one has disappointed me in its quality when I hold it in my hands. I can't say that about the Rossi's. I don't own one, and thats because every one that I've examined just doesn't have the same quality feel of my NEF's. Also, and this is very important for a "first gun" that will hopefully become a treasured heirloom someday, the NEF's are an American Classic--American Made and a tradition when it comes to these single shots. The Rossi's are just a johnny come lately knock off import.
As to the safety, I guess it can't hurt, but with the NEF transfer bar, its unnecessary. Just don't cock the hammer until ready to fire. Does the Rossi have a transfer bar safety to protect it when dropped? If not, then the NEF is a safer gun. Also, when I was a young one starting out with an old Stevens 20ga single shot in the squirrel woods, I wasn't allowed to chamber a round until a squirrel presented itself. This a good procedure I feel with kids. Obviously won't work with bird hunting or rabbits, but is a good way to start them out on squirrels.