@jon_5912 that sounds right. From Richard Hardesty in APJ Vol. 3:
Vented subwoofers offer inferior performance compared to sealed enclosure subwoofers of equivalent quality in the following areas: transient response, phase response, group delay,and low frequency extension. You might ask why anyone would choose to make a vented subwoofer. There is one very good reason—high output. The one advantage that vented enclosure designs offer is a reduction in cone excursion at low frequencies.Reduced cone excursion allows vented designs to play louder. A side benefit is that reduced excursion will also produce lower steady-state harmonic distortion measurements.
and Hardesty in his review of the Thiel CS6 in APJ Vol. 8:
They have vented bass loading utilizing passive radiators rather than ports. Alignment is unusual and bass is tightly controlled with little evidence that the enclosures are not sealed.
So, Hardesty was a big fan of sealed enclosures (and even bigger fan of Vandersteens) yet he implied that the Thiel's passive radiator sounded not too different from that of a sealed enclosure. In turn, this implies that Thiel's passive radiator is a "good" trade-off between sealed and ported enclosures. At least that's *this* bozo's take :^)