Hi blueorchidz,
The Arctic Dreams uses a high performance polyfoam which isn’t actually memory foam and as he mentioned is more resilient or “springy” than memory foam (see post #2 here).
I would also make sure that you find out the density of the foam layers in the Copper Gel memory foam mattress (or any mattress) before you purchase it.
I would be cautious with other people’s opinions about firmness because different people can have very different perceptions of firmness and softness compared to others and a mattress that feels firm for one person can feel like “medium” for someone else or even “soft” for someone else (or vice versa) depending on their body type, sleeping style, physiology, their frame of reference based on what they are used to, and their individual sensitivity and perceptions. There are also different types of firmness and softness that different people may be sensitive to that can affect how they “rate” a mattress as well (see post #15 here) so different people can also have very different opinions on how two mattresses compare in terms of firmness and some people may rate one mattress as being firmer than another and someone else may rate them the other way around. This is all relative and very subjective and is as much an art as a science.
Phoenix