Hi goofinky,
Welcome to the Mattress Forum!
Both of the items you’re considering use good quality and durable materials, and their products possess good “safety certifications”, and as you’re probably aware both manufacturers are site members here, which means that I think highly of them and that I believe that they compete well with the best in the industry in terms of their quality, value, service, knowledge, and transparency.
There is more information in post #2 here and the topics it links to about mattresses and children and “suitable” and “safe” materials including a link to some general guidelines for children in post #2 here. It also includes a number of links to the better forum posts and topics about mattress and children as well which have more information about many good options children which would be well worth considering.
The only reliable way to assess the “safety” of different materials in more general terms is based on lab tests and the certifications they have for harmful substances and VOCs (regardless of whether they are organic or natural or synthetic) so that you have some assurance than the VOCs are below the testing limits for the certification. There is more about the different types of safety certifications such as Oeko-tex, Eco-Institut, Greenguard Gold, C2C, and CertiPUR-US in post #2 here and more about some of the differences between organic and safety certifications in post #2 here and there are also some comments in post #42 here that can help you decide whether an organic certification is important to you for environmental, social, or personal reasons or whether a “safety” certification is enough.
You’re not “nuts” at all to be concerned for the health of your child, although I know there is quite a bit of “fear mongering” online that may “drive you nuts” :blink: trying to decipher its validity.
All mattresses emit VOC’s – it doesn’t matter if it is synthetic or natural or blended (even fruit emits VOC’s,) so there is no such thing as a mattress foam that emits no VOC’s that are the same as background levels. It’s really a matter of whether the VOC’s are harmful and if the foam is certified, at which point most people would be comfortable with the amount of VOC’s that are emitted.
Also, there are no spray-on chemical flame retardants used in wither of the mattresses you are considering.
In the end, any mattress that uses materials that are durable enough and are in a suitable firmness range and that has a reliable safety certification and you consider to be safe enough would be a suitable choice for a child.
Phoenix