Hi corey and welcome to the Mattress Underground
Glad to see you are researching your new mattress - an informed consumer is the best consumer!
As you likely know, any any mattress you find to be ideal will be based on your Stats (height, BMI, sleeping position(s) and any underlying health conditions), and your PPP (Posture & alignment, Pressure relief, and Personal preferences). You may want to take a look at the Mattress Specifications You Need To Know and see how they compare to the Mattress Durability Guidelines. As you can see, latex is one of the most durable mattress materials available.
Your current Sleepy’s Slumber Plush mattress consists of gel infused memory foam, soft and HD quilted foam all of unknown composition and density, and a 5 zone encased coil support layer. If you enjoy the feel of latex, either of the listed mattresses should be a considerable improvement, with the increased breathability and durability latex entails. As long as you can match the comfort and support levels to your body profile, Sleep On Latex and EarthFoam carry solid quality latex sleep solutions; EarthFoam also is organic, with their 8.5" mattress consisting of organic latex, organic wool batting, and an organic cotton cover. Quite a different feel from a hybrid memory foam mattress!
Any mattress you purchase should have a list of recommended bases that will not potentially void any warranties… The Costco Sleep Science Q Series adjustable base has:
Multiple head/foot lift positions
Zero gravity preset
Legs adj to 3", 6", 9", 12"
While the Sams Club Members Mark base is a more ‘stripped down’ adjustable base:
head and foot articulation
zero gravity preset
Adjustable bases are all similar in respect to their construction, with a metal frame, and fabric or upholstered covering that usually has a ‘no skid’ top surface the mattresses lay on. The big consideration here is whether the adjustable bases comply with the mattress manufacturers recommendations - maximum weight is one major factor they consider in their approved bases. The Costco seems a better fit from an objective standpoint as the legs allow height adjustments in increments of 3". Your Mattress Firm Deluxe metal platform is a simple wire gram base, and lacks the adjustability of the other bases you are looking at. While it appears it would be insufficiently sturdy for an all - latex mattress, again, you may want to check if this would be an approved base for the mattress you purchase, just to be sure. And you may also want to take a look at the adjustable bases offered by many of the Trusted Members of the site, to see if any of these compare more favorably to your requirements for an adjustable base. In any event, it sounds like you are well on your way to a sleep solution that will provide many years of great sleep! Please feel free to share your experience once you had some time on your new mattress.