iTUSA Academy just opened a new facility near Phoenix and my son and I got to be among the first to play on their red clay. They have red, HarTru, hard, and a grass court to be completed in the spring.
We are no strangers to red clay as we often play in Germany in the summers while visiting family. Also played a lot of HarTru when we recently lived back east. Red is certainly stickier than HT, which does make the balls heavy, but I've played courts on both surfaces that are prepared very differently. iTUSA's red clay, for example, has less "surface" than those I've played in Germany - almost as if there is a hard court under it and some clay on top. I think they are still working on the court. The German courts are thicker and softer. The HT at our club near Philly had a lot of surface and was irrigated from underneath, so it was always moist and thick as opposed to some HT that gets watered twice a day by hand and plays dry and fast. Just an obvious observation that court build and prep makes a significant difference in how they play.
Oh, and red clay stains everything!