Scary Mattress!!

happywife2b

We have a Vera Wang feather topped mattress that is so soft we often roll to the center and smush together in our sleep. Since we are planning to bed-share for the first few months this mattress must go. I just freak out worrying that the baby will roll into the hole (depressed center, not actually a "hole") and suffocate. I want a memory foam mattress, and would love input from anyone who has one. How do you sleep, do you get a hole in the center where everyone ends up? Is it soft enough? Too soft?

I bed-shared with #1 so I know all about the safety issues, guidelines, etc. I just want info on the mattress. Thanks in advance!