Which mattress and spring tension?

Good morning, after many hours of research I still come back to your web page. I am currently in two minds weather to purchase your 002 or a similar Hypnos.
I am looking for a super king, our details are, 5'11 and about 14.5 st and 5'8 and about 12.5 st and at our age the weight is only going one way! We liked the Hypnos in the showroom (can't remember model to hand but about £2500) However it was described as medium to firm, yet we found ourselves thinking we wanted it a little firmer. Could this be it had been abused/old? Also how long is your lead time?
many thanks,
Simon.