@gdnrbob said: "I think the Vandy subs will be a better integration than the HSU's- which are running parallel to the speakers, so there is some overlap, which I think muddies the sound."
If you have a phase control on the Hsu's, you may be able to find a setting where there is enough partial cancellation between your mains and subs that you won't have over-emphasis in the region of overlap.
Duke