Don't know. Theortically, and based on a few actual use reports, the .400L is better overall than the 300Whisper, 350L, 360BH and .450BM. Recall that some states have a max length, as well as straight wall, that nixes the 300W and .450BM.
I have built and tried them all, including a bunch of others, except the 400L. When it came out...
But I told myself NO. I've experimented enough with new, heavy bullet AR15 cartridges. Plus, I have 2 10mm DI AR15s, a Marlin 35Rem, a Henry .41Mag and a Henry .45-70 and I don't live in a straight wall state. I have literally no good reason to try a 400L except that I really like calibers that start with a .4.
IF, ballistics mattered more than marketing, we'd be devoid of about 30 modern cartridges, but we all know that is not the case.