Hi ps9915,
ILD/IFD is only one of several specs that makes one material feel softer or firmer than another (see post #4 here) and the ILD or IFD of different materials or different types and blends of latex may not be directly comparable to each other (see post #6 here) so how closely your proposed layering compares to your previous layering would depend on how closely all of the layers compare to the layers they are replacing…
If the actual ILD of a Dunlop layer is the same as the ILD of a Talalay layer and they were both measured accurately using the same method of testing ILD then it’s likely that the Dunlop layer would feel a little firmer to most people (a good ballpark would be about 4 ILD firmer).
There is also more about how Dunlop compares to Talalay in post #7 here and in addition to any differences in actual firmness they will also have a different “feel” which may also affect how some people rate them in terms of firmness as well.
Foamorder would be more familiar with the specific firmness of their layers than I am and they would be a better source of guidance about how their layers would compare with the ILD of the Talalay layers you are replacing.
Since this is the same layer as you are currently using it would feel the same.
This would depend on whether the actual ILD was closer to 24 or to 28. If it was closer to 28 it would likely be “similar” to a 30 - 32 ILD layer of Talalay and if the actual ILD was closer to 24 it would probably feel a little softer.
Deeper layers will have less effect on the feel and firmness of the mattress “as a whole” than layers that are closer to the sleeping surface but if you add about 4 ILD to this layer you would have a rough comparison to the Talalay ILD you are replacing (which I don’t know) so once again it would depend on whether the layer was closer to 30 ILD or 36 ILD. This is also assuming that you would feel relatively small differences in a bottom layer.
This would give you a way to compare them “in theory” but the “bottom line” is that the only way to know for certain how it will compare to the current layers you are sleeping on and how well you will sleep on the new layering will be based on your own experience because some people may be more sensitive and notice differences that may not be noticeable to others.
Phoenix