You will still get more tactile feel from the Servo15, and you won't have to calibrate for two. Two subs that aren't collocated can cause cancellation and be tricky to get right, especially if you have a less than optimum room. Do you plan on doing measurements and adjustments for proper placement of the two subs within the room? If not, I wouldn't get two. Why not a VTF-3 HO?