But its humid there  in NC  one thing I am not sure people understand is PA has the very best weather In the entire WORLD...

Carpet will mold due to humidity.

If you install during the hotter season you risk the floor most likely gapping and coming apart during the winter or buckling during the inverse.If you are set on some type of hard surface flooring a dehumidifier could help reduce some of the risk for the time being, since changes in humidity and moisture are actually what cause expansion and contraction not temperature, they usually are just tied hand in hand.The larger the room the more the floor will move.

we've ran into houses with no power (it's 95 degrees and humid in Florida, you need A/C).. houses with urine stains and smells.  

Have you checked humidity levels inside of the building?

They do exactly what they are designed to do, heat and cool without having to run ductwork.They might not control humidity all that well.But they almost always use less electricity than ducted HVAC.

Humidity, heat, and no air movement = problems!

It seems that the most important part is the quality of the paint especially if the house gets lots of sunlight.My house is located in Alabama, so it is hot and humid in the summer and cold in the winter.

You'll love Charleston as long as the summer heat and humidity doesn't do you in.    

As to climate control, I havent asked about it, but have seen the humidity control as you mentioned for "business storage" options.