The general consensus seems to be that the newer powders in the Reloder series are less temperature sensitive than the older ones, but still somewhat more sensitive than some other powders - especially at the upper end of the safe pressure range. Since this is where it really matters, this is good to know.
Years ago, when Hodgdon first started selling their Extreme line of powders ( and the short-cut powder kernels ) I was working with RL19 in the 30-06. I got good accuracy, as well as good velocity, but when it got hot outside, it got pretty erratic. The pressure spikes were kinda spooky. My buddy showed me some test data from an independent lab, and it told the story. He had this data ( which he got from Hodgdon ) because he was using RL22 in his 30-06, and had seen the same thing I was seeing on hot days. Well, he just backed off on the powder charge, and kept using the RL22, because velocity was still better than with other powders - and accuracy was phenomenal. I switched to H-4350, and never looked back - excellent accuracy, very good velocity, and no more worries about having a problem on an early-season antelope hunt.
Now I'm working with a new rifle, in .280 Remington. Same basic cartridges case; smaller hole in the end. I think this may lead me into powders that are slower-burning than my favorite H-4350, but I'm still going to try that one first. I'm thinking H-4831, or maybe even H-1000. ( I'm using the Hornady 139-grain GMX.) If I go to a heavier bullet, the slower powders will almost certainly come into their own over the 4350 burning rate. It will just be a matter of whether or not I can get enough of it into the case. Any comments for me ????