I'm not sure. However, now that others have indicated that the HE-6 felt was a pre-production version. However, here is how the HE-5LE was implemented. As to benefits, changes - improvements, or not, it is about a $1.00 cost, for materials. The only thing lost is time.
Also, while I did sell my pair of HE-400s, I didn't leave the HifiMAN family. The HE-4 model was purchased yesterday and the HE-5LE was paid for today. The HE-4 headphones are in my home now. The HE-5LE will arrive later this week. I'm reluctant to share too many observations between the HE-400 and the others as this process will take a bit of time to start to document these variations. Also, while my HE-400 was sold, I do have access to a pair of HE-400s for all side-by-side comparisons.