Just got done testing these guys. I'm listening to a recording of the Atlantic City Convention Hall's pipe organ, Blower startup demonstration, Tocatta in D minor, Hymn: Abide With Me, and of course, the 64-foot Diaphone (8hz, I believe?) and several others. You do not get more bass than this.
My opinion is that the ER6i actually needs a bit of air space to recreate bass properly. The tighter the seal you can get the better, of course, but it does need to be a ways from your eardrum.
With this setup, I still find that I don't get much bass (sorry, no scientific tests). I've had the pleasure of listening to said tracks on a surround sound system with an excellent receiver and subwoofer system, and it will literally shake windows and raise the hair on your neck. It's barely audible with the ER6i until the volume is increased to the point where recording hiss is clear. Turning on the Bass Boost equalizer does help, but it's not a perfect fix.
Hope that helps.
ER 6i from Etymotic Research - I can't hear you! No, really, I can't hear you!!