Hi Venexiana,
Welcome to the Mattress Forum! 
Both FSF and SleepEZ are site members here, as you’re probably aware, which means that I think highly of them and their advice, and I wouldn’t hesitate recommending them for your consideration. They both also have much experience with those in a higher BMI range.
Localized testing, especially with the special challenges of a higher BMI, is extremely valuable. Savvy Rest uses good quality natural Talalay from Radium. If it helps you in comparing what you may have tried in the showroom versus your own creation, the firm Talalay from Savvy Rest is generally around N8, and the medium is around N7. The soft is around N5, but from your configurations I don’t think you looked at anything using that layer.
There’s certainly no reason you couldn’t choose an all-Talalay mattress. The differences in compression modulus you spoke of will be less evident with higher ILDs, and also less evident in the lower support layers of the mattress. Both Talalay configurations you listed would certainly be in the firmer end of the spectrum, and generally provide enough layering for someone in your BMI range. Your first configuration would lean a little more toward a firmer “deep support”, but both would be supportive.
With the FSF, I always recommend to strongly consider the recommendations of a manufacturer, as they are best suited to put forward choices that they believe will give you the best chance at success, and what they present will also be combinations that they are most comfortable making with the componentry they offer. The FSF combination you presented would for most people have a firmer overall comfort than the similar ILD all-Talalay configuration you listed.
There’s a few posts that describe a similar situation to yours, specifically post #2 here and post #3 here (and the posts it links to ) that you may find useful.
You’re choosing between good quality materials, so I would lean toward what you’ve personally tested and liked and try your best to approximate that, as nothing can replace your own careful and personal experience. I would also make sure that you are completely aware of any company’s layer exchange/return policy, should things not turn out as well as you had hoped.
I’ll be interested in learning of your progress and any decisions you eventually make.
Phoenix