The only SVS cylinder I have heard is the 20-39PC+ I bought to try out last October.

Using my VTF-3 as the constant, the PB1+ and 20-39PC+ sound extremely similar if not the same.

The PB2 box subs....the ISD, Plus, and Ultra are even bigger than the PB1+.

The cylinders take up less floor space, but are tall....that 16-46 will be 46" high.