That's a great point on the EP0. If you want portability, that's the way to go. I can't be lugging my 30 pound powered sub with me.

Regarding the SPL levels, it's really difficult to judge performance with recorded music because you don't know what reference level it was recorded at. Peak levels for example may be recorded 10dB down from 0 reference (or maybe 20dB down judging from your readings). I would think the best way to judge would be to use a test CD that is known to be recorded at 0dB in a room that is much larger than the speakers themselves. And the speakers would have to be placed well away from room boundaries. I've been using the Realtraps test tones off of their website for these kinds of purposes.

House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated