I have never personally tested both ELD-X and ELD-M side by side on game. We always just shot the ELD-M because it's nearly identical to the old AMAXs we had such great luck with. From everything I have gathered, they will cause more damage at like 700+ yards compared to the ELD-X. They both will have the same affects at shorter ranges, but they say the ELD-M does better at longer ranges. The ELD-M is also available in more bullet weights and has higher BCs compared to equal ELD-X bullets. The ELD-Ms also seem to shoot better and are more consistent than the ELD-X bullets from my experience and research.