Only issue i find with a drysuit in warm climates is the out of the water. It can be uncomfortable in the sun, you can sweat making it damp and clammy and so on.
I've been surprised from the very beginning how comfortable the 30/30 is ABOVE water. Have worn it in full-sun 90F+ with no problem. In fact I've been much hotter and more uncomfortable in a 3mm wetsuit while gearing up and waiting to enter than I've ever been in the DUI.
The material is a "breathable" trilam (DUI's "Tropical Dry" technology) and really seems to work. As you can see in the picture I posted, laying in the sun in the noon sun at +85F with the top of the suit simply zipped down is plenty comfortable. In fact, I never once sweated in the thing the whole week. That includes jaunts up and down 1,000 Steps, Karapata, and rock-climbing in and out of sites like Bise Morto and some other unmarked sites up in the park and elsewhere.
The thin Capilene 3 top and bottom I wear underneath is great on the surface because it allows wind to flow through and sweat to evaporate, but blocks the sun effectively.