Tremendous race from Warholm and Benjamin here. What I saw from Warholm the last time out in 47.26 was not nearly as impressive as this. In the previous race, he was stretching to retain his stride pattern in the last 100m and not very smooth. Here he got out extremely well, yet was able to speed up in the last 100m and looked extremely smooth over the last barriers to virtually negate Benjamin's greater flat speed at the end. He continues to surprise with his improvement. It looked like Samba and Benjamin would dominate for the next ten years. If Samba, who has already broken 47 (last year, I believe), is healthy for World's, it will easily be the strongest 400mH competition ever and the world record should go down.
Warholm has been experimenting with how to approach the last 2 hurdles this year.
The 2 last races prior to this he has gone 13 steps all the way, but as you can see from Paris his frequency goes down.
This time he went back to his old formula of 15-15 last two hurdles, resulting in him stuttering on the 9th (probably changed his mind between hurdles).
Anyways, with 15 - 15 he looks smoother as you say, but no doubt he'll need to do 13 all the way to keep the speed up enough to hold of Benjamin (and Samba).