the he400i is really beautiful!!!
but i think there are many headphones out there that are very versatile & can do it all.
that's weird.
I feel like flagship headphones may have a certain tonality or sound signature, but they perform admirably across all genres & all applications (music/movies/gaming) as long as you like their sound signature.
Considering that flagships have better sonic qualities (like clarity, detail retrieval, sound stage) than mid-fi headphones and are often tuned to be more neutral, I don't really understand that kind of thinking. If you have a pair of neutral headphones, I don't see how they can be unsuitable for certain genres as they portray the song as recorded. If a pair of headphones have a weakness for me (eg. anemic bass or too bright), it's a dealbreaker across all genres.
I do like to have a pair of reference headphones that I am very familiar with compare new headphones/amps/dacs against, but if I find something I like better, then I would just switch over to the new pair. I've tried the multiple headphones for multiple applications, but personally found that I just ended up sticking with the headphones I like best.