@audioconnection , you took the words out of my mouth.
The limitations are that there are certain frequencies that get attenuated too much, despite careful setup. The result being that one setting will sound great with Classical, but become boomy with Pop and Rock. Using the Vandy sub has never shown this behaviour.
Another benefit of Vandersteen subs is that they are built like tanks. 2W's are still working despite being nearly 30 years old, the 2wq's are a bit younger, and I expect they will last just as long. Hsu and SVS are good subs, but I don't think they will age as well.
I still think you should join the Vandy forum and get some more ideas or at least explanations. Though we love our speakers, we will provide honest answers.
Bob