Hi Tommybo,
Welcome to the Mattress Forum! 
Having a bit of a higher BMI presents special challenges and generally requires firmer materials (in the support layers especially), and this would also apply to your even more so as you sleep on your stomach and your wife ends up on her back or stomach as well.
This could be firmer latex or innersprings (the type of support component would be a personal preference and in the right design either could be suitable) or even a zoned construction. The same overall guidelines apply with higher weights though that PPP (Posture and alignment, Pressure relief, and Personal preferences) along with using high quality durable materials that will maintain their feel and performance for longer periods of time are the way to make the best choices. Heavier people in general will need firmer and thicker comfort layers and firmer support layers than those who are lighter and because no materials will last as long with much higher weights the quality and durability of the materials and components is even more important than normal, and considering latex (with or without a spring unit) certainly would be a good starting point. Post #3 here has more information and suggestions about heavier weights that is worth reading.
If it is a “typical name-brand” innerspring mattress, you certainly would be near the end of a normal expected comfort life for such a product.
SleepEZ offers many different types of latex, including Dunlop, Talalay, natural or blended, organic certified and/or Oeko-Tex certified. The biggest difference in feel would be between Dunlop or Talalay (Dunlop being a bit less “bouncy” feeling than Talalay), and these foams can be had in different softnesses. The difference in certifications would be more of a personal preference and not necessarily an issue of quality. Most people that are looking for an “organic” mattress or materials are usually concerned more with “safety” than whether the materials have an actual organic certification and they usually aren’t aware that an organic certification isn’t the same thing as a safety certification. There is more information about the three different levels of organic certifications in post #2 here and some of the benefits of an organic certification in post #3 here and there is more about the different types of organic and 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.
SleepEZ is a member here, which means that I think highly of them. Their mattresses are a component system, so if you’re considering them your next step should be a detailed phone conversation where you can explain what you’re trying to achieve and they will then be best able to offer you their advice regarding what they carry that they think would provide you the best chance at success.
This is obviously a totally different product form the SleepEZ, being more of a traditional memory foam mattress. The 8" 2.4 lb. polyfoam base uses a good quality material, but the 3" of 3 lb. memory foam on top would provide me pause, especially for anyone over 200 lbs. or so. I’d prefer to see 5 lb. memory foam in your application.
This is again a bit of a different mattress, although closer to the BedInABox than the Sleep EZ. A forum search on Purple will also bring up much more information and feedback about them as well. They are using a layer of buckling column gel which is a good quality and durable material. There is more about buckling column gel in this article and in post #2 here and the posts it links to and a forum search on " buckling column gel " (you can just click the link) will also bring up more comments and feedback about it as well. The buckling column gel is 2" thick and then there is a 3.25" layer of 1.8 lb polyfoam under the buckling column gel (this may be 3.5" thick because they list two different thicknesses in their FAQ and the description for each size) and a 4" 2.0 lb polyfoam base layer which are both good quality materials so there are no lower quality materials or weak links in the mattress that would compromise the durability or useful life of the mattress although I would add a caution for those that are in higher weight ranges (mid 200’s or higher) because of the 1.8 lb polyfoam comfort layer.
Whether or not you are picky, you still want to make sure that whatever you are purchasing uses higher-quality materials. You’re a bit “all over the board” with items you’ve suggested as far as componentry and feel, so my best suggestion would be to find a local retailer where you could perhaps test out items that are at least similar to a latex and a memory foam bed to at least “get an idea” as to a feel you might desire.
The best advice I can offer you is to reread the Mattress Shopping Tutorial and follow the steps in selecting a new mattress. At the end of the guide is a simplified version of selecting a mattress, and for those who want the SIMPLEST VERSION OF ALL …
Choosing the “best possible” mattress for any particular person really comes down to FIRST finding a few knowledgeable and transparent retailers and/or manufacturers that sell the types of mattresses (see this article ) that you are most interested in (either locally or online) and that can provide you with all the information you need to know to make an informed choice and make meaningful comparisons between mattresses and then …
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Careful testing (hopefully using the testing guidelines in this tutorial) to make sure that a mattress is a good match for you in terms of “comfort”, firmness, and PPP … and/or that you are comfortable with the options you have available to return, exchange, or “fine tune” the mattress and any costs involved if you can’t test a mattress in person or aren’t confident that your mattress is a suitable choice.
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Checking to make sure that there are no lower quality materials or weak links in a mattress you are considering relative to your weight/BMI range that could compromise the durability and useful life of the mattress (see the durability guidelines here )
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Comparing your finalists for “value” based on #1 and #2 and all the other parts of your personal value equation that are most important to you.
Phoenix