I couldn't say for sure - Like I said the pre-production had more "perceived" bass, but it sounded like it was just a tad warmer than the revised model. So perhaps they're the same or even the new one has more. The pre-production felt just a little fatter in the bass, perhaps? and the new one maybe with just a little more perceived clarity. It wasn't a huge change, but the revised one sounded ever so slightly clearer to my ears (and I tried both the new ones HiFiMan had there)
Like I said, the differences were not night-and-day, but I imagine anyone chasing that thicker signature would be happier with the 400i anyways. YMMV.