Hi odrunr,
Just in case you haven’t read it … the first place I would start your research is post #1 here which has all the basic information, steps, and guidelines you will need along with links to some of the more important forum posts that can help you make the best possible choices.
As you will see … I would also suggest avoiding any of the chain stores such as Mattress Firm. At the very least I would make sure you can find out the specifics of all the layers in any mattress you are considering before making a completely blind purchase where the odds are high that you would either be purchasing a mattress with lower quality materials or a mattress that has poor value compared to many other similar options that are available to you. You can see some comments about the YuMe mattress in post #2 here. I believe the prices for the YuMe mattresses are rather outrageous.
I would also take some of the claims you are mentioning and the marketing information you are being told with extreme skepticism and a big grain of salt.
I would also consider buying a mattress for your “regular” needs (with her back sleeping) and then either adding a topper for the extra pressure relief your wife will need while she is pregnant because you will have the mattress for much longer than she is pregnant and it’s not really possible to “fix” a mattress that is too soft without removing and replacing materials. You can remove the topper after she has the baby if she no longer needs the extra pressure relief. I would also consider using a body pillow or a pregnancy pillow while she is pregnant to improve both comfort and support during the more “awkward” staqes of pregnancy. Back sleepers generally need thinner or firmer comfort layers than side sleepers and stomach sleepers generally need thinner/firmer comfort layers yet to avoid the risk of sleeping wit the spine out of alignment. I would also avoid memory foam if you plan to have the baby sleep on your mattress because it is too movement restrictive and too soft for babies and young children IMO.
I would also not translate higher cost as meaning a more suitable mattress and I would make sure that you don’t buy any mattress where the type or quality of the materials inside it is unknown regardless of the “story” attached to it. Again … I would particularly avoid the YuMe mattress unless you are able to find out all the detailed specs and there is a compelling reason that for some reason justifies their prices for what are basically memory foam and polyfoam layers of unknown density. If they can provide the specs but don’t know what they mean you are welcome to post them here and I’d be happy to make some further comments.
You can read a little more about various ways that can be used to cool down memory foam in post #6 here and more about the many factors that can affect the sleeping temperature of a mattress in post #2 here.
You can read more about adjustable bases and some online stores that are good for pricing references in the adjustable bed thread here.
I’m not sure exactly where you are but some of the options listed in post #4 here may also be within reasonable diving distance and worth calling and/or visiting.
Phoenix