Less pressure would be a good thing, assuming that pressure is a problem in the first place.
In years of reloading the 458 Win I have never experienced problems with excess pressure.
Problems to do with limited case capacity when using some powders, yes, but overly high pressure signs, no.
Regarding heat, Africa is not the only place with high temperatures.
When I first worked up loads with 500's at 2100 plus in the 458 I did it in outback Queensland January heat which is often over 100 F, and sometimes closer to 120 F in the shade.
There is no shortage of extreme heat during summer in far west Queensland.

The Jack Lott buff incident has been mistold many times.
You need to read the entire story to understand what really happened.