Hi pedzola,
I would probably agree that this mattress (or others that are similar or that use the Cloud Luxe as a reference point) may be too soft for those that are in a higher weight range. As you also mentioned … the softness of a mattress and how far you sink into a material can also affect sleeping temperature (see post #2 here).
These can both be “side effects” of this type of softer memory foam design and that a mattress that was a little firmer (such as a mattress that was closer to the Tempurpedic Rhapsody or some of the others in the Contour collection) may be a better choice.
Thanks for the feedback 
Phoenix