Hi jerbear,
Welcome to the Mattress Forum! 
I’d be cautious about using industry designations like “firm” or “plush” as absolute guidance, as there are no “standard” definitions or consensus of opinions for firmness ratings, and different manufacturers can rate their mattresses very differently than others so a mattress that one manufacturer rates as being a specific firmness could be rated very differently by another manufacturer. In addition, different people can also have varied perceptions of firmness and softness compared to others and a mattress that feels firm for one person can feel like “medium” for someone else or even “soft” for someone else (or vice versa) depending on their body type, sleeping style, physiology, their frame of reference based on what they are used to, and their individual sensitivity and perceptions. There are also different types of firmness and softness that different people may be sensitive to that can affect how they “rate” a mattress as well (see post #15 here ), so different people can also have very different opinions on how two mattresses compare in terms of firmness and some people may rate one mattress as being firmer than another and someone else may rate them the other way around. This is all relative and very subjective and is as much an art as a science. In other words … the only reliable way to know whether a mattress will be “firm enough” or “soft enough” for you will be based on your own careful testing or your own personal experience. In lieu of that, I would suggest a phone call placed directly with any manufacturer you’re considering and describe what you’re trying to find in comfort, and they’ll be best able to advise as to whether their offerings are close to what you may desire. Many online manufacturers offer a variety of comfort choices with their “simplified choice” products. You may also inquire at that time about any potential return/exchange policies should your purchase not turn out as well as you had hoped.
There is a listing of some of the common “distruptor” mattresses that you mentioned in theSimplified Choice Thread here. You may also wish to look at some of the online site members listed in post #21 here, who are all very experienced and knowledgeable and specialize in providing the type of help and guidance on the phone that can help you make good choices. There are a wide range of latex and other options included in the choices there and I believe that all of them compete well with the best in the industry in terms of their quality, value, service, and transparency.
You can see some of my comments in post #3 of this thread regarding fabric movement on any mattress placed in an adjustable bed situation. It’s generally not a concern for the majority of people.
Phoenix