There are newest technology comparison (Oticon Intent vs. Phonak Audeo Infinio Sphere) out of curiosity (ceteris paribus rule, 2cc coupler):
Acoustic input for Oticon Intents: 60 dB
There is a difference, especially in 3-5.5 kHz range.
However, IIRC, all balanced armature technologies originated from Knowles. I wonder what makes the distinction. And of course I wait for xMEMS technology.
Sources: