Artisan Mattress softer than Origins 1500?

Dear John & Ryan
We are currently using a Vispring Marquesss Superb in a Kingsize with medium tension but for the last 6 weeks or so, I have been waking up every morning with lower back pain. We already own an Origins Pocket 1500 with a medium tension which we have on a spare bed which feels considerably firmer than the Vispring mattress so we switched he mattresses & my back pain stopped after a couple of days. The Origins Pocket 1500 feels just a bit too firm to both of us so we are looking for a mattress with the same level of support but with a softer comfort layer & we're thinking either the Artisan Natural or the Bespoke 004 would fit the bill. I weigh 11 stone & my wife 9 stone.