Hi tekila1,
I think when it comes to the whole subject of softness and firmness it's usually best ... and safest ... to go by each person's personal experience. What one person calls soft or even "too soft" will often be called firm or "too firm" by the next person. Much of this depends on body type and sleeping position and the construction and layering of the mattress as well as the softness that someone is used to and that they use as a reference point for their "softness" terminology. In other cases though ... even people that you would think should have similar perceptions can be very different.
As you also mention ... there is always the variable of how much a mattress in a showroom has softened (or become firmer in some cases if there is fiber in the quilting of if there is a layer of very soft foam over very firm foam which softens and allows the firmness of the deeper layer to come through more). Latex will soften less than other materials but it will still soften to a lesser degree. Other components in the mattress besides just the latex will also "break in" during the first few weeks.
For example ... most people would call the Edsele quite firm (which is also how Ikea rates it) however you experience it as fairly soft.
This is further complicated by sometimes inaccurate ILD ratings or ILD ratings that use different methods to assign an rating. For example ... if the mattress at Ideal is "Sri Lankan" latex and is really 4.6 lbs cu/ft (74 kg/cu meter) ... I would have a very hard time believing that it really is 18 ILD (more likely in the mid 20's range) and yet you still feel it as being soft when others may also experience this as a relatively firm mattress. As you can see on the
Latex Green site
... they list this density as being 13 - 18 kgf (kilograms of force) which I believe sometimes gets "translated" into 18 ILD when its not. They don't even list the ILD although some distributors will test it with their own equipment.
In addition to this ... with the 1.5" of quilting foam that Dreamfoam uses ... the effective ILD of the upper layers would already be softer than the ILD of the latex that was being used.
When you are testing locally ... then ILD ratings are really not relevant because your body will tell you what is soft or firm and the numbers that are attached really make no difference. Some people will also be more sensitive to surface softness and "rate" the softness/firmness of a mattress based on this while others will be more sensitive to the deeper layers and their rating will depend on how far they feel themselves sinking down overall.
So all of this can be quite complex and subjective and has many variables but overall I believe it is far better to err on the side of firmness which can be easily "fixed" and fine tuned than to err on the side of softness which introduces some challenging complexities and is much more difficult to correct if you make the wrong choice.
For most people ... I think 19 ILD (which is the ILD of the Talalay that would be used in the softest versions) would simply be too soft in combination with the soft quilting except for some lighter and curvier side sleepers that were used to softer mattresses.
When it comes to mattresses ... it can be very "risky" IMO to go by other peoples perceptions which may be completely different from your own (even if their body type and sleeping positions are the same). Specific patterns of feedback if the numbers are large enough may be helpful if enough people identify the specific mattress layering and their own body type and sleeping positions but this is fairly rare in reviews. I think the two safest methods of making the best choice are either to trust your own personal perceptions with accurate testing that takes at least 15 minutes on a mattress fully relaxed (if you are testing locally) or to go by the "averages" of the manufacturer of the mattress in combination with any feedback you may have if you are making an online purchase.
I think that the most common "mistake" that people make is buying a mattress that is too soft ... usually in the comfort layers ... but also in the support layers because they like the "showroom feel" which often doesn't translate into the best sleeping experience in the long term.
Phoenix