Hi steven_sharma,
The latex that is used in the Ikea mattresses is a continuous pour Dunlop manufactured by Mountaintop Foam. They use a continuous pour system manufactured on a belt instead of a mold which can result in a little bit better consistency throughout the core in terms of ILD because the latex particles don’t settle as much. To answer your question directly … it’s not “worse” than other types of latex and like all latex they are a good quality product. I would probably lean slightly towards 100% natural Dunlop made in a mold because it would be slightly better quality (natural latex is generally more resilient and durable and has better overall performance qualities than synthetic latex) but the difference would be slight with an 85% natural blend. It is also OekoTex certified. I would pay a slight premium for 100% natural Dunlop but not a significant one. You can see some of my thoughts about the Ikea mattresses in post #3 here.
As far as I know … the Edsele is C3 in terms of firmness (they have a range from C0 - C5) which by their ILD measurement would be in the mid 20’s which means it would be somewhat “softer” with initial compression on top but would get firmer as you sink in more (Dunlop has a high compression modulus which means it gets firmer more quickly as you sink in more deeply). Their ILD’s can’t be compared to other latex ILD’s though because I believe they use a different method of testing for ILD than other latex manufacturers (there are many differences between ILD testing used around the world) and their 24 ILD would be a firmer ILD compared to other manufacturers.
The best question you can ever ask is “why” and it’s great to see that’s just what you are doing 
Phoenix