The TAC-50 kill you speak of
was indeed the longest range kill in combat, until a shot by a 338 Lapua beat it earlier this year. Here is a few links:
New longest kill shot by sniper
Hotshot sniper in one-and-a-half mile double kill - Times Online
The alarm went of on you the most when you referred to a Khan, instead of a Kahn. Its the 338 Kubla
Kahn, not 338 Kubla
Khan which is nothing more than an improved 338-378, which yes will shoot flatter than the Lapua, but not so with the Lapua Improved. It seemed odd that a guy saying he owned one couldn't spell it right. Then again, we all make mistakes.
On paper, you may be right about the Weatherby. In the field, I have found way different situations. Maybe it has to do with the quality of Lapua components being much better than Weatherby's (a FACT), maybe familiarity with my rifles (only shot the Weatherby a few times, and never in a hunt). Whatever the case, I prefer the Lapua as far a long range accuracy goes. Sure the Weatherby is faster, but it isn't more accurate, and it isn't just me that will say that. I do know that accuracy concerns and feeding problems with belted magnums and wildcats is not a new thing. It was a concern with the US Military had with the weatherby when they had RAI design the the 338-416 before Lapua redesigned the cartridge with the help of Cooper from Accuracy International. And I'm sorry, that is a weighing factor. Hitting a human at range is much more difficult than hitting an elk at range.
On that note though I will acknowlege you could argue the Weatherby is the better hunting gun, because in hunting you don't have to be as accurate. It still doesn't make it more accurate
Bottom line, the LM is more accurate and stable at long range. I would love for you to prove different, and not just state ballistics comparisons at muzzle point or 400 yards, which I'm sorry, isn't long range hunting.