I'm taking a hard look at the Velodyne DLS-5000R at future shop with the price drop. Less than half price. I've seen some reviews that say that they are not as good as the SVS or the HSU's in the 15-30 Hz range but shine at 40-60.
Choices... choices
I bought my first 5000R for 800 bucks, my second one, a thousand bucks.
for 400+ bucks, I'd buy one for each channel
the port is tuned to 30hz, but I believe there's an EQ boost lower than that.
so yes, the SVS and HSU's will go way lower, but its a tradeoff thing ... lower tuning = less loud. more loud = higher tuning.
oh and the 5000R have always had the 1000w amp (not the 600w specs rating); same amp as the SPL-R series.