Mac,
I'm not looking for a shitfight here but there are a couple of things I feel need saying.

You are correct that the 458 has too small a capacity for easy and efficient loading of the 500gn bullet to the original claimed velocity.
You are correct that the 458 Lott has the powder capacity to easily and efficiently get that original claimed velocity and more.
You are correct that the Lott is a more efficient cartridge than the 458 Win.
You are correct in that if Winchester had made their 458 on a longer case it would have achieved the claimed velocity and may have avoided the problems encountered with the standard length case.

You are IMO not correct in saying that the 458 cannot do what Winchester claimed it could do.

Graeme Wright claims that many NE cartridges actually produce 80 to 100 fps LESS than the claimed velocity which were originally taken from pressure barrels of usually 28 inches or more.
Wright states that 470's are sometimes around the 2025 fps and this would be in 24 to 28 inch double rifle barrels.
Back in the early 90's my back up rifle was a 458 Win Mag custom Brno and I did quite a lot of shooting with it.
I cronographed quite a lot of handloads and also some Winchester factory stuff.

Late 1980 production factory Winchester 510 softpoints chronographed at between 2020 and 2035 fps.
BUT, this rifle only had a 22 1/2" barrel!

My handloads ran at 2120 fps for 500 Hornady and Woodleigh softs, and I used a different powder for solids which cronographed at 2080 fps in that 22 1/2" barrel!
All handloads had the bullets seated to achieve the standard cartridge overall length.

So IMO the Winchester factory ammo was equal to the ACTUAL 470 NE power level and my handloads EXCEED it!

Both Boddington and Lott have canned the 458 Win in print yet they have also stated that the many African PH's rely on the 458 with factory ammo for back up work on DG.
Yes 458 rifles are cheap to buy and 458 ammo is readily available and this would be a good reason for the 458's popularity, but...
Does this mean that all the pro's who choose the 458 are backing clients up with a problematic cartridge capable of hangfires, over high pressures and lack of penetration, simply because the rifles and ammo are easy to get!

Or do they use 458's because they are easy and cheap and THEY WORK!

Also Boddington claimes that some factory ammo he crono'd was a tad under 2000 fps and he claims that this puts it into the 450/400 energy class.
Ha!
What he fails to mention is that he is comparing ACTUAL cronograph readings for the 458 against CLAIMED velocity for the 400!
Graeme Wright has cronographed quite a few 400's and has found that ACTUAL velocity for this cartridge is usually around 2000fps!

Now Mac, many people including yourself have high praise for the 450/400 NE and its reputation would have been made on many occassions with a 400 grain .411 bullet at around 2000 fps.
So I would have to ask why the 458 is so inefficient and unworthy when it can push a LARGER DIAMETER BULLET which has a full 100 GRAINS MORE WEIGHT at THE SAME VELOCITY with FACTORY CARTRIDGES?

I believe that if you do a FAIR comparison using ACTUAL VELOCITIES fo ALL cartridges used, the 458 can do what was originally claimed when it was released, and that was to equal the power level of 450 NE or 470 NE while using a case which could operate in a standard length action!

Mac, I agree that physics don't change.
But gunpowders do!
If they didn't we'd still have to wait for the smoke to clear before firing the second barrel!

With todays powders it is easier to achieve the velocity in the 458 needed to make it equal in energy to the old NE loads!