This is mostly correct, except the notion that sealed can have better dynamics in mid-bass; they don't. They simply have similar dynamics, although they still may be shy a dB or 2 from their ported brothers. As for the sealed version of any sub going down to 19Hz, forget about that. Many manufacturers use equalization to boost the low-end response of their sealed subs. While the sealed sub can maintain that response at a low drive level, it very quickly compresses past moderate loudness demands. I wouldn't expect much output from the SB-2000 Pro below 35Hz or so, maybe just a little bit.