I have a memory foam matress and I love it. I bought it 5 years ago due to back issues, and the matress has helped enormously. If i'm staying elsewhere, I always look forward to coming back to my own bed! I'll not buy a normal mattress again.
I haven't found it particularly hot, but I usually lie on my side while hugging the duvet, because I generally get hot at night, but I'm the same no matter what the mattress.
Happy mattress hunting!