Good bullet, good shooter, good result.
Those are important compoents, but you forgot one. When using something pretty far to the light end of the spectrum for the job, the additional factor you need is a very cooperative elk that gives you the opportunity to put those other 3 to use. The likelihood of that depends much on location: terrain and cover. They matter with all cartridges and bullets to some degree, but the smaller you go, the tighter the window gets.
I've thought very hard about chucking all my other hunting rifles and going back to a .257 Roberts ... but I notice that I haven't actually done it yet.
