I have received the FAD Sonorous VI's, and they're a very energetic-sounding pair of headphones. The balanced armature architecture gives it a very smooth, strong treble and midrange, and the dynamic driver fills out the bottom end very well. These headphones are by no means "flat". The bottom end is, as far as I can tell, a bit north of neutral, but not greatly inflated. The bass decay is NOT the fastest, but is punchy-sounding enough for most situations with fast bass attacks. It does not intrude on the mids whatsoever.
I listened to the track you previously linked to this discussion page (Good Times Roll // GriZ x Big Gigantic) and can tell you that with the Sonorous VI's, your genres will sound drier and leaner. This issue may be exacerbated by your Amp/DAC (i.e. Audioquest Dragonfly v1.2 known to be drier and leaner, but when I switched to my Creative Sound Blaster X7 LE, it was much warmer sounding). Simply said, in a toss-up the TH-X00's will mostly likely be the headphone you'd want to go with.
In a macroscopic view, the Sonorous VI's aren't an extremely detailed headphone. It won't be able to retreive as much micro-detail as, say, the Sennheiser HD 600, 700, nor 800, but may be on-par with the HD 650's (from my estimates). However, it will sound much more detailed than the V-Moda M-100's and slightly more detailed than the Sony MDR-7520's. By my observations and others' reviews, I believe the Sonorous VI's to have better, more articulate highs than the Fostex's, but the Fostex's to have a more dynamic bass and a smoother and warmer sound signature, more suitable to your listening. If you wanted better mids and highs for, say, classical music, or for a more balanced, detailed sound, I would definitely go with the FAD Sonorous VI's.