Hi TiredinLaffy,
Unfortunately Chuck is right because if you add a firmer layer over a softer one it will compress into the softer layer below it and only put you further away from the support layers of the mattress. This means that you would be sleeping on a firmer surface but you could still be sinking too far into the mattress which won’t improve support … except perhaps slightly. the firmer layer on top would slightly reduce the amount the softer latex compressed but it would also give you more thickness to sink into before the support layers “stopped” the heavier parts of your body from sinking in more. There’s more about this in post #4 here.
The difficulty with a comparison between the Ultimate Dreams and the PLB is that the ultimate dreams has 1.5" of soft quilting foam on top which effectively makes the comfort layer softer and thicker than the ILD rating of the latex alone. I suspect though that you would have had similar issues on the Beautiful because this has even thicker/softer comfort layers before you get to the firmer latex on the bottom.
You could try a 2" - 3" firmer topper but this is unlikely to make a significant difference in support because it will put you even further away from the firmest support layers at the bottom of the mattress and if you did decide to try this then I would make sure the topper was refundable because it would be an experiment with low odds of success.
Another option would be to try a topper made of compressed natural fibers such as wool or silk (again making sure it was refundable) which could also slightly reduce the amount you sink into the softer layers. It will also get firmer as it compressed over time but once again you would be sleeping on a firmer surface (although some people love the feel of a wool or silk topper) and you wouldn’t really be improving the support of the mattress.
Just to be sure I am understanding you though … are you sinking into the mattress too far overall (leading to poor alignment) or are you “going through” the top layers and feeling the firmness of the support layers below it and causing pressure relief issues from feeling the firmer support layer (in which case a topper may help).
If it is a support issue … then I would consider taking Chuck up on his exchange offer which is very generous because he will likely end up losing money on the whole transaction.
If it is a pressure relief issue that needs more softness/thickness in the comfort layers (like the Beautiful) … then a topper would probably help.
Phoenix