My .458 Alaskan had just a bit of capacity over the .458 Win Mag and easily did over 2,200fps with 510gr. Winchesters.
It also easily did over 2,400fps with 400gr. using Barnes data for .458 Win Mag.
The "bad rap" as I understand it, was due to bad or poor storage of ammunition, which downgraded it's ballistics and also caused miss-fires.
Until that happened, it was well reported on, seems to me as it's ballistics met or achieved most of the DG Rifle ballistics of 500gr. bullets at 2,150fps.
There are no flies on that ctg today, except perhaps when it is downloaded on purpose.