I have heard that and was/am prepared for that to possibly be. I really like Nosler partitions, but a recent experience has me interested in the ELD-X (this could be in a different thread).
I was going on a hunt in Texas with my dad and brother. Initially, we were going to hunt Nilgai South of Corpus Christi, so I got some 250gr Nosler partitions for my .340 Wby Mag. That hunt fell through as I was landing in San Antonio, so my dad hooked the three of us up on a Scimitar Oryx management hunt near Junction. My brother shot an oryx at about 200yds with his 6.5 CM using 143gr ELD-X loads. He didn't have enough power for an immediate kill despite good shot placement and required a follow up shot to dispatch. While gutting the oryx, the ELD-X expanded nicely and did quite a bit of internal damage before lodging on the inside of the opposite shoulder.
Post oryx, we're trying to find the herd again so I can get one when an elk herd pops out of the trees about 150yds out. Elk cows are cheaper and bigger than oryx, so I shoot one of the cows with the .340. Exit hole is slightly larger than the entry hole despite taking out ribs on both sides. I take another elk cow later that day at 100yds, same story. No expansion on either partitions.
I'm thinking that the Weatherby mags are just moving too fast at that short of a distance to expand. Rumor is the ELD-X will expand at high speed, so I'm willing to give it a try. As long as accuracy doesn't degrade too much.