I've owned a 390 for a few years now and it has been a great gun. I don't really know the difference between it and the 391.
That's the same thing I have heard repeatedly that they are great guns.. I don't think there is a lot of difference between it and the 391 except the shape of the receiver and the valve. What's funny is the Walmart gun is MADE IN ITALY and the 3901 series guns are American Made yet the American gun costs 200+ more dollars at most gun dealers. I would rather have the italian made gun.