Hi tarpon21,
Hopefully you’ve read the tutorial post that dn linked and once you get to step 3 then the better options and possibilities in the South Florida area (assuming you are in or around Miami / Ft Lauderdale) are listed in post #2 here. I f you are close enough to Miami then one of the members here (Select Foam) has a showroom there where you can make side by side comparisons of their mattresses with the Tempurpedic line.
This mattress uses high quality memory foam (5.2 lbs) and has no obvious weak links so it would be a durable choice yes although I would also test the roughly equivalent Tempurpedic to make sure it is suitable for your needs and preferences in terms of PPP (Posture and alignment, pressure relief, and Personal preferences).
I would also read post #4 here and the links it includes before you consider Dynasty (which is not made in North America).
Only the members here offer The Mattress Underground discount although it never hurts to ask. I would also treat the extra 5% as a perk rather than one of the most important factors in your purchase. Outside of Dynasty I wouldn’t hesitate to purchase from any of your choices with or without any additional 5% or any bonus that they offer.
Outside of the South Florida options I linked the tutorial post that dn mentioned has a link to some of the better online memory foam sources that I’m aware of.
Phoenix