Hi Brian -- Thanks for your question. I'm afraid we have not done an in-depth review of either of the Jamison products you asked about, so am not able to speak to them with nearly as much detail as I can the Zenhaven and Avocado. (As an aside, you can find our review of the Zenhaven on this site already. Our review of the Avocado has been completed and will be published here in the coming weeks. See the links to these below.)

• Zenhaven mattress review
• Avocado mattress review

That said, I have had a chance to lie on various mattresses in the Jamison TLC line, and have also spoken to the company about this product line on multiple occasions. Looking at the two models you are considering, it seems they are both all-latex models (whereas many other Jamison TLC models are latex over polyurethane foam), so that aspect is similar to both the Zenhaven and the Avocado.

However, IIRC Jamison uses synthetic latex (a petroleum-based product), which is certainly a key difference from both the Zenhaven and Avocado, both of which use 100% natural latex (i.e., latex made from the sap of a rubber tree). It is possible that Jamison uses a natural blend latex (which is typically about 30% natural, 70% synthetic), but I highly doubt it since they would almost surely mention this on their website, which they do not, and I don't remember them mentioning this when I spoke to them either. Natural materials or chemical content may or may not be important to you, but this is certainly a factor that affects the cost of their underlying materials. In addition, there are many people within the mattress industry who feel that natural latex is also a better-feeling and longer-lasting product.

On a related front, the Zenhaven and Avocado also both feature organic materials in their cover and quilting (e.g., organic cotton and wool), whereas the Jamison products do not. The Zenhaven is also flippable, which is not the case with the Jamison models (or the Avocado).

While there are surely many other more nuanced differences in terms of comfort, feel, and other characteristics, I'm afraid I can't speak confidently to how these specific Jamison models compare on those fronts. Sorry I can't be of more help on that. I hope the rest of this answer was at least somewhat helpful for you though.