Hi nanbees,
If they are accurate (which sometimes isn’t the case), if they use the same method of testing ILD, if the materials are the same (type and blend in the case of latex), and the only difference between two mattresses is the ILD of a single layer of the same thickness, then a comparison between them would be more meaningful (see post #6 here and post #4 here).
The perception of softness and firmness is very subjective and can vary from manufacturer to manufacturer and person to person and different body types and sleeping positions will also have an effect on the perception of softness and firmness so this is the “norm” in the industry. What feels “way to soft” for some people can feel “way too firm” for others. There are also different “types” of softness that can make a difference depending on what each person may be more sensitive to (see post #15 here). The only thing that really matters is what you personally experience as being soft or firm.
Yes … an “all latex mattress” outside of thinner mattresses that use @ 6" or so of latex or that use mostly synthetic latex or are “latex hybrids” would be difficult to find in your budget range outside of some of the lower budget choices in the posts I linked in the last reply.
Phoenix