I'm a purist. Current taste clearly leans heavy on the bass, even bassheadss say so. Then the idea they would set the EQ to fit some average rooms sonics to make people comfortable as opposed to shooting for purity/ accuracy is bogus. They could easily supply both curves. Notice manufacturers are not following suit (skull candy type crap not included). You can prefer what you want.
As for HFM cans every HFM head I know ( me included) will tell you the long cup cans (HEX 1&2, HEK 1, 2, SE, Ananda, Arya 1 & 2, MD XX) all lack bass impact compared to the HE-6, and many agree the HE-6SE v1 & v2, and HE-500 have more impact and certainly better timbre than those long cups. Your better bass by larger drivers works pretty well with dynamic drivers as long as the magnet is strong enough, the throw is long enough, and the material doesn't deform with low bass signals. There is something lacking in the long cups - it's not stage size, it's bass impact not bass going down down to 20 Hz or below. They are well built so they can take +10 at 25 hz, but db is not impact. There are likely over 500 posts on Head-Fi discussing that.
Haven't heard the XS but based on what I read it does not appear to exceed the bass impact of those long cups I listed - except perhaps the Ananda/XX, and HEX v2. I'm glad you like it that is all that matters in terms of enjoyment. My search is a bit different. Ciao