I only heard the Sage for a few moments, nothing long term, but here are brief thoughts on the FR of the upper midrange to treble between the Savant (gift from Wizard), Sage (auditioned briefly), and Noble X (sample from Massdrop):
2.5k to 5k: Savant > Sage > X
5k to 8k: Savant ≈ Sage > X
8k to 12k: Savant > Sage > X
12k to 16k: Savant ≈ Sage >> X
The Sage, to me, has slightly smoother treble than the Savant but is in general similar. It has more forward mids and more tamed upper mids, which makes it a more pleasant sounding earphone (to my ears).
The Noble X, to me, has more recessed mids and upper mids than both the Sage and Savant. It has a more present lower mid presentation than the Savant, but has quite a bit more bass.
Of course, the Savant is now discontinued in favor of the Sage. The Noble X does *not* have that similar of a presentation to the Sage. The bass is somewhat similar in quality, but because the mids and highs between the two models are quite different, the quantity of bass seems fairly different. The Noble X will have more perceived bass than the Sage, less forward mids than the Sage, and more relaxed treble. Personally, I would prefer the Sage to the Noble X, but that's not to say others won't feel the opposite. The Sage is more forward and full in the mids, and that's its bread and butter. The Noble X is a little more V-shaped, but doesn't have grating highs or anything disturbing like that. Because the mids take a slight backseat, the texture of the bass will come out a teeny bit more. JM2C