Mattress Foam Certipur certificates and side sleeper advice

Hi, I'm 6'1" tall, 12.5 stone and primarily a side sleeper. The Artisan Naturals looks wonderful but a bit out of my price range, so i'm considering between the Origins 1500 and Artisan 1500. I've noticed the Artisan has a firmer upholstery. Would the Origins therefore be the safer bet, or is the increase in firmness only slight?

I've also noticed that some manufacturers label their foams with certificates(e.g. certipur), and since the Origins Pocket 1500 uses a foam insulator, I was wondering whether you could provide more info about you own foam and safety standards. Maybe its all just marketing nonsense but I though I'd ask before making any decisions.