Hi rconn,
N1 would probably be on the softer end of the scale in terms of averages yes but it would also depend on what was over or under it, on the thickness of the layer, and on other factors because ILD is only one of several factors that can affect the perception of softness or pressure relief (see post #4 here). Body type and shape, weight distribution, sleeping positions, along with individual preferences and sensitivities will also play a significant role.
Phoenix