Hi ZhivagosGirl,
I think the Jordan Brothers would make a good choice … although I do understand the difficulty of the final elimination process 
While I wouldn’t tell you to step away from the Ikea store and they are “better than average” value … I believe that what you are considering is superior to either of the Ikea Dunlop latex mattresses you mentioned. Of course if either Ikea mattress was clearly superior in terms of PPP (Pressure relief, Posture and alignment, and Personal preferences) then that would make a big difference but all other things being equal … I personally would tend to go in the direction you are going … especially because you have tested it and it “works” for your needs and preferences.
Foamed latex is quite different from the type of dipped latex (such as gloves, condoms, and other more solid latex products) that some people are sensitive to. A type IV sensitivity is to the latex proteins on the surface and these are mostly removed in the foaming and washing process. It would be very rare for people with a latex sensitivity to have any issues with latex foam and I know people who have been selling latex mattresses for decades and have never encountered a single instance. While anything is possible, the odds are very small indeed that there would be any problems.
There’s more about this in post #2 here.
Phoenix