Hi CeruleanBlue,
If you are thinking of an online purchase anyway that you can’t test in person … then some of the options listed in post #21 here may be worth considering.
Sleeptek certainly uses good quality materials but they are not the best value in an apples to apples comparison with other choices you have that use the same or very similar materials.
I would say the odds of a “good latex mattress” (Talalay or Dunlop) that didn’t have very soft layers on top lasting 14 years or longer are much higher than with any other material and barring any “unknowns” it’s very likely yes (see post #2 here which compares different types of latex along with post #4 here and the posts it links to about the factors involved in durability).
Phoenix