Hi furkidzmom,
I would encourage you to visit Yankee mattress and talk with Nick in spite of your friend’s experiences (although I don’t know the specifics). They are good people and very knowledgeable about mattress materials and what makes a good quality mattress and have some good quality and value there. I would doubt that your friends are aware of mattress materials and foam quality or have much knowledge about what makes a good mattress unless they have spent many years in the industry so they may not be the best source of advice (although again I don’t know the specifics of their experiences). NOTE ADDED: They are also now a member of this site
MEK is just a company that sells some of the mattresses they make.
A mattress is only as good as its construction and the quality of the materials inside it so it would depend on the specifics of the materials inside any mattress you were looking at.
The good news is that they will tell you the specifics of what is inside any of their mattresses which means that you would be able to make meaningful comparisons with other mattresses in terms of quality and durability and they will also educate you about the quality of the materials they use.
That’s a very broad question because gel foams are an entire category or materials and it includes many different types of foam. It depends on the specifics of the gel materials but you can read more about gel materials in general in post #2 here and more about the factors involved in the sleeping temperature of a mattress in post #2 here. Again though … there is lots of information in both posts so I would just read it to get a broader overview of some of the gel related or temperature regulation information rather than study it. There is a lot of “hype” about gel materials in the industry but it also has some benefits (temporary cooling for a while until temperatures equalize and adding a little extra support to memory foam for example) and your best source of accurate information is talking with “experts” that are familiar with the specific materials they use in their mattresses rather than becoming an expert yourself.
Phoenix