My conclusion would be to use both a dehumidifier and an air purifier. I use both, and my air purifier increases humidity a bit. Run them on opposite sides, in a circulatory pattern if possible. Since heat rises put the dehumidifier higher than the air purifier. The purifier will cleanse the air from the ground up and allow the air to be clean and dry or clean and wet. Depending upon various circumstances.
Short answer to the question would be yes. It will help to prevent mold. Keeping temperatures cool, maintaining clean dryish air is all that's needed.
I have noticed the Ionizer function being taken off of certain Honeywell models, I wonder if there are some health concerns when using them or if they weren't cost effective to produce?