The wing loading is not that simple, although, for the most part it is a "close enough" approximation to be useful for some comparison.

The wing loading is just the ratio of mass to wing area. i.e. 20oz/sqft. All this tells you is how much lift the wing has to generate to be able to fly level. If all planes had the same wing shape (and size), then your suggestion would be true, but because all wings are different, then the Actual lift generated is different per plane, and thus the "stall speed" is different.

By way of a simple example, Flaps are control surfaces that change the airfoil shape of the wing. The move down, creating a wing that generates more lift. The flaps do not change the weight of the plane, and they do not change the surface area of the wing either, but they DO reduce the stall speed of the plane. Thus, althouth wing loading is a useful figure for a lot of things, it does not have a direct bearing on the stall speed of a plane.

On the other hand, similar wings with similar wing loadings will produce similar planes.... to a significant extent anyway.

Also, one othe thing... The lift generated by a wing is actually more closely related to the wing volume than the wing area... The wing volume is harder to calculate, so it is seldom used in places like RC hobbies. Anyway, a wint with a 10oz/sqft loading that is 1ft wide has very different stall speeds than a wing that has a 10oz/sqft loading that is 5ft wide with the same airfoil shape.

gus