Hi EMC10,
I personally wouldn’t use any slow recovery foam or “soft” foam (and they would all qualify as “soft” when they are warmer) for a baby and I would also be very cautious with it for an older child that is still growing as well (see post #2 here).
Of course this is about their own mattress but if they would be sleeping with you on a regular basis then I would be very cautious with it in the parent’s mattress as well.
The better options or possibilities I’m aware of in the new Orleans area are listed in post #4 here.
That’s great … I see your already ahead of my suggestions 
Phoenix