Hi hardtotell, and welcome to the Mattress Underground 
Great to hear you have had a good experience with Rest Right. I’m not familiar with the company, but a couple replies in This Post share some positive experiences consumers have had with them. Keep in mind that any mattress you choose will be unique to the sleepers sleeping on it, based on their Stats (height, BMI, sleeping position(s) and any underlying health conditions) and their PPP (Posture and alignment, Pressure relief, and Personal preferences).
I took a look at the Rest Right Kingship Comfort and it looks like a well constructed mattress, it’s three 3" Dunlop latex layers of 18, 24, and 32 ILDs. This gives you the option of switching the plush, medium and firm layers around if you need to tweak the ‘feel’ of the comfort layer. The Serenity latex is Talalay latex, and is flippable, with 1" plush and 2" medium firm IFDs of 19 and 24 on both sides surrounding a support core of HD foam at 2.5lb/cuft. You can compare these against the Mattress Specifications You Need To Know and the Mattress Durability Guidelines.
Latex is one of the most durable mattress materials available - though Dunlop and Talalay have very different ‘feels’. Talalay is considered ‘bouncier’ than Dunlop (the difference is as between angel food cake and pound cake). Some consumers prefer one or the other, but if you enjoy the feel of the Rest Right Kingship Comfort it meets our criteria for quality, and as you say, it does allow the ‘fine tuning’ of a DIY without a lot of the trial and error that such a project can entail. I would make sure to check with them (if you haven’t already) that the mattress is compatible with your intended adjustable base so that you don’t void any warranties or return policies in case you need to exchange or return it.
Perhaps other forum members with experience with Rest Right can also chime in as well. Please let us know your experience with your new mattress once you’ve had some time with it!
~ Basilio