Others say it's a slight V or U shaped FR. To my ears, it sounds reasonably balanced in that I don't find any area of the spectrum really overtaking the rest with the kind of music I listen to.
Bass is there, but it's not really pronounced like the HTF600, especially in the sub-bass region. It certainly doesn't detract from the mids.
As for smooth vs. sparkly treble, I haven't honed my audiophile sense enough to pick out one or the other yet, but one thing's for sure: no dynamic I've heard has sparkling, revealing clarity like a Stax Lambda (any of them), and the Uptown hasn't changed that. Has your experience with the HE-400 similarly spoiled you when it comes to traditional dynamic/moving-coil drivers?
I tried gaming with it some more, and the positional cues with DH are there if I listen for them. But they seem to get lost in the mix during a heated firefight unless you're paying attention, exactly the moment where you DON'T want to have issues with knowing where everything is coming from. The soundstage seems a bit oval-shaped, with front and rear being the short sides. Clearly, soundstage that's acceptable for general stereo music listening just doesn't cut it for gaming with any sort of binaural HRTF surround mix.
I've never heard an ES7 or M50, so I can't comment on those.