Rogue,
It was a totally informal study, but I asked an outfitter from Colorado who has had years of experience and lots of hunters over the years, what Weatherby calibers he saw most often for his elk hunts. It really surprised me, but he said the .257 Weatherby was the number one (more recently the .30-378). I asked him why he thought that was the case. His response, easy to shoot and easy to hit with, which he thought made his clients more effective, (no flinching). I don't know if you could call it the best all around elk caliber (that should generate lots of debate) but with good bullets and proper shot placement, there's no reason you couldn't take the biggest bull in the woods with it. The .270 Winchester has been doing it for decades, and the .257 Weatherby generates similar numbers comparing 130 grain versus 120 grain Nosler Partition bullets.