since you said it would be used mostly in humid south, here is my thought:   single wall part is the rainfly/roof  - you may get a lot of condensation there, regardless of the ventilation

I only have one single wall tent - a Black Diamond Firstlight which uses Epic fabric, which is not even totally waterproof - i.e. it breathes.  I do get quite a bit of condensation inside when the temperature swing is large enough - if cold enough, the inside can get coated with frost.  SIL-nylon isn't breathable at all as far as I know.

Otherwise, I have 5 Sierra Designs tents, and all have given me good service (haven't used the 3 man tent yet) and been dependable.

check and see if you can find any gear reviews for the tent you want