I'm not a big flash bang high speed magnum needing guy. That said, the 26 Nosler is a very capable elk round, if, you feed it an elk bullet, then put it in the elk where it belongs. Anyone that tells you differently is either uninformed or unknowlingly commenting on their marksmanship. My son's 260 Rem, with pedestrian 140 gr. corelokts, kills them very dead. Both the 26 Nosler and the 260 Rem shoot a .264 caliber pill. But I'd suggest both need different pills. Do I chase elk with 26 caliber, nope, I use a 28 caliber on them, as my son does now that he is an adult, unless we pack a 27 or 30 caliber rifle.
If you must use the 26 Nosler for elk, consider picking a tough built bullet with a good SD, then it will work fine. That said, I do think your 300 WM is a better elk round. With a cartridge as fast as the 26 Nosler, there are two things it will be very tough on. 1. Your barrel. 2. Your bullet. A third is likely your ears. About the time you plan to launch a 1/2 mile shot, your bull will appear at 50 feet, covered in mud, better have a bullet up to that. Odds are this round is a speciality/novelty, my guess. Do you hand load? Only time will tell if the 26 will stand the test of time, I suspect it will end up as a novelty.