If you have a sheet, then the comforter, you can always toss the comforter aside. I’m also a person who always has cold arms, so I wear pajamas with sleeves to bed every night, so it’s easy for me to become too hot at night if I have all the blankets and stuff on top of me. You might not find it too hot if you wear less clothing and have only a sheet on you.
As for too much give-- no, that’s definitely not a problem.
My husband radiats heat like a human furnace so I fear that we’d both suffer if the bed retained that heat. Overstock.com has one that is advertised as being “cool”. I’m going to have to research the return policy before we purchase.
I need a new bed though. I am not sleeping well at all.
Lindsey Wagner is taunting me daily with her sleep number bed ads but hubby and his ex got a sleep number bed about 2 weeks before they split up and now he’s just not willing to travel down that road again.
The problem I have is that I sleep on my side and my shoulders are fairly broad and my hips rather narrow. Yet it’s my waist area that heats up the most, causing the memory foam to compress more in that area than near my shoulders, where the foam stays fairly stiff. As a result, by morning, my upper back (at the bottom of my shoulder blades) is extremely stiff and sore because my waist and hips are so much lower than my shoulders.
They’re extremely comfortable to lay on when I first get into bed. But not so great when I look at the bigger picture of a full night’s sleep.
We have a full Tempurpedic mattress, not a topper. I know Ohio isn’t exactly a “warm climate,” but it does get fairly hot and muggy in August. We are both very hot people and produce a fair amount of body heat. We do not have a problem with the bed being too hot.
The salesman that sold us our bed told us, in fact, that a local couple returned their bed because it was too cold. Make of that what you will.
I’ve only ever slept on memory foam in San Diego and Tucson, AZ. Never had a problem. BTW, yes, use a mattress cover.
I dunno, I’ve never had sex with my bed. 
In all seriousness, no, they’re just fine. Better, actually.
Get a sheep wool fleece mattress cover, the thicker the better- if you slepp hot on any sort of mattress. The real stuff- not synthetic. Cool in summer, warm in winter.