I wasn't going to post as the OP asked for real experience, but as there's been other discussion, I feel bolder to comment.
The history of the 458 Win Mag has fascinated me for some time. I have a fun conspiracy theory about the original production runs of the factory ammo that Winchester Western put out in this chambering: the line manager was a drunk, a junkie, or received his position without sufficient qualifications via nepotism or the like. In Pierre Van Der Walts African Dangerous Game Cartridges, the author brings up an astonishing anecdote:
"Daan van Heerdan and I once pulled bullets from still sealed boxes of old Winchester .458 factory ammunition. The results were perplexing. I could not believe that coming from the same box, some cartridges were loaded with ball propellant and others with extruded propellant! How that happened I cannot explain. Measuring the ball loads and extruded loads separately we could not even determine what the intended load for each was supposed to have been! This variation was consistent with all the old boxes we checked that day." African Dangerous Game Cartridges p. 325-326.
Also observed in that book that some of the ball powders used had coatings on the balls that would cause the powder to clump so bad as to cause incomplete combustion, sometimes resulting in muzzle velocities ~1600fps... blackpowder range...
Van Der Walt goes on to say that while the paper performance of the chambering may be a bit mundane in comparison, it sure has piled up the pachyderms through the decades. Richard Harland's favorite rig back when he was ivory hunting in Dande in the Zambezi Valley was a BSA .458WM with a 5 round magazine. He observed that he would be dead many time over if he had chosen a double - too little capacity.
Of course everyone remembers Capstick's classic (in Death in the Long Grass) anecdote about Zambian elephant cropping and continuously reloading a Model 70 with two or three rounds such that the bottom cartridge bore dozens of recoils such that its load became compressed and almost cost the cropper his life.
The beginning of the end of the 458WM's reputation was Jack Lott and his mouthpiece of Guns and Ammo. While on a buff safari with Wally Johnson in Mozambique, Lott put a "soft" though the ribs and into the paunch of a buff. Lott's second shot was a solid through the shoulder. Johnson then puts seven rounds of 375HH into the buff, then takes Lott's .458WM and shoots the buff two more times. Poor initial shot placement and substandard ammunition. The only logical course of action is to blame the chambering!
I think anyone bashing the 458WM in quality factory ammo or hand loads loaded with good bullets is a keyboard warrior. I'd imagine in a standard length action one could be quiet handy.
Of course, if one's 458WM is already in a magnum length action, the reaming job to make it a Lott probably won't hurt anything. Even with shorter barrels, the Lott is a little easier to get desired velocities from hand loads with lower pressure to boot.[/
Seriously, can't make out what sort of black and white beast that is.
