That's an exceptionally perplexing statement to me because the RS1 was such a bassless experience I felt like I was listening to an answering machine. Then again, a mix between "treble cannon" and "warm and full" would be about what I recall as my experience with the HE400 (not the -i).
The 400 may go as "deep" as the LCD-2, but it does so with not a fraction of the authority. That driver might be vibrating, but the party isn't making its way down my ear canal.
The RS1 has a strong mid bass presence to me. Sure the bass and sub bass aren't very prominent but I wouldn't call the RS1 bassless. All I am saying is that the 400i is a mix of the RS1 and LCD-2 sound. very good bass and sub bass extension like the LCD-2, a bit of a mid bass hump like the RS1, mids are not as flat as the LCD-2 but not as prominent as the RS1, and the treble is also the same as it has the extension of the LCD-2 but a bit brighter. Not quite as bright as the RS1.