I always questioned the accuracy of Etymotic bass because it never seemed to resemble what I would hear in a live setting. It was always anemic.
I deduced that this was due to the absence of a viciseral (sp?) effect of the bass which can be simulated much better in dynamic driver headphones.
It also makes me think the "accuracy" measurements are based strictly on tonal accuracy yet everyones reference point for bass MUST have a certain element of tactilness to make it seem real.
This is why there is a need (IMHO) for a bass boost as long as it doesnt bleed into midrange.
My contention is that a BA IEM can surely have a bass boost and still be very very accurate.