I own a DD, and the last thing this breed is is soft.
They don't tend to do too well in heat however. Lots of guys own them in the south, and they'll be able to speak to it better than I can, but my DD absolutely hates the heat. That said, he's never shut down in it, and will go as long and as hard as I let him.....which is why you need to watch this breed to prevent problems (both with heat and other things like injuries, etc.).
Personally, if I lived in south I'd opt for the Deutsche Kurzhaar (DK). Bottom line is the german testing/breeding system works. That's not to say they are better than any other well bred gun dog, but the system is built around testing for, and producing results, and more often than not, it achieves that. Same would hold true for a NAVHDA GSP. http://www.nadkc.org/
One other point...my DD is my buddy 12 months a year, my hunting buddy for 3 months (First time owner btw). DDs and DKs have a ton of "get up and go", and there's reputation out there that they are too much to handle, or too demanding, or not good house pets. I've only seen that opinion expressed by people who have never owned one.