Hi pengles/Paul,
Welcome to our forum 
!
Your question about thickness is a good one and you can see my thoughts about the effects of thicker layers or a thicker mattress in post #14 here. More individual layers would give you more options to customize the “feel” and performance of the mattress either before or after a purchase which can be a great benefit for some people that need to fine-tune their mattress for best comfort/support. Regardless of how thick or thin a mattress may be, the most important part of the “value” of a mattress is how suitable it is “as a whole” for your particular body type, sleeping positions, and preferences in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences). These are all good questions to ask the SOL themselves over the phone as they will know first hand about those differences based upon the information you provide them and their experience with similar somatotypes and sleeping postures they can best recommend a configuration using their componentry that they think will suit your particular needs.
If you decide to go with either of the Sleep On Latex mattress, make sure to email Scott (at) themattressunderground (dot) com to get your discount code. (He is checking the discount emails about 3 times daily.
Good luck with finding the best product for you and I’d be interested to find out what you decide.
Phoenix