Looking at the Artisan range, want a medium/medium-firm comfort.

Hi, from reading all the information on your website, we are considering the Artisan Naturals or the Artisan Tailored Pocket 2000. We want a medium/medium firm comfort level with excellent support (sleeper 1: 6ft 3, 16 stone, with lower back problems and mainly a back sleeper; sleeper 2: 5ft 8, 11.5 stone, mainly a side sleeper). We are also considering the Top Dog mattress from Loaf having tried it in store, although are concerned it may be slightly too firm. What advice would you give? Also, would all these mattresses only be effective with a divan base? We like some of the Made.com storage beds however they have slatted bases. Thank you.