Hi cbb,
Your experience is interesting and really goes to show that the person on the mattress and how well a certain combination of layers works for a particular person can be just as big a part of the useful life of a mattress as the mattress materials themselves (see post #2 here).
If I’m understanding you correctly your old Sensus topper on your son’s extra firm base works well for him (he’s thrilled) so the combination would still have some life left in it if he is the one sleeping on it.
On the other hand … the same mattress doesn’t work quite as well for you (although you “could” sleep on it) but if you replace the old Sensus with the new Sensus on the same base foam then it there is “some improvement” for you which seems to indicate that the difference between your old Sensus and your new Sensus is the main reason for the improvement since they are both on the same base foam.
Thanks for the feedback … and I’ll be interested to see how the new base foam works for you.
Phoenix