I agree with your impressions word for word.
Pretty much every genre of music I've listened to on the HE-400s has been brilliant, except for rock which seems to be hit & miss depending on the recording.
My top 3 genres for the HE-400s are:
1. Goa Trance - Deep basslines, atmospheric synths, psychedelic vocals and catchy melodies all meld together so beautifully that I'm often closing my eyes and drifting off into another realm.
2. Jazz/Accoustic with vocals - I'm not the biggest fan of this genre as none of my previous setups have quite done it much justice. All I can say is nothing I've heard does vocals (especially female vocals) as well as the HiFiMAN planar series. Anything from Norah Jones' heartwarming, angelic voice to Paco de Lucias lightning quick flamenco guitar is simply breathtaking.
3. Tech House/Minimal - Nothing brings out the clean, fast bass like a bit of minimal or tech-house. It's not just the bass line that's in focus here though - vocals and ambients are really transparent and present without any separation issues with the deep, thumping bass-lines.
I agree with Norah Jones' voice being excellent on here. Most of my music is without vocals, and there are a few vocals that are sort of a miss, though opera tenors are spectacular. I find it funny that headphones with this signature are generally passed on by the audiophile intelligentcia in favor of brighter, more neutral headphones (T1, HE-6???) for the audiophile staples of jazz & classical. It makes me wonder if any audiophiles have ever actually heard a live orchestra or quintet