Can't help you with this comparison, but I am using VSM-MX with a Velodyne DD-15. The digital interface and ease-of-setup with the DD-15 is remarkable. With the BBAM you need to use line-level inputs to the sub. The crossover is centered at 30hz with 12db slope. I would have crossed over even lower, except that in my room, some EQing was necessary to fill a dip in response in the 40-50hz range. With a 30hz crossover there was just enough sub output left in this range to be elimininated with the sub's parametric EQ. Frequency response is now flat +/-2db from 15hz up.
Using the spectrum analyzer of the DD-15 with the sub output turned off, I was impressed to see that the VSM-MX alone made useful bass to about 27hz. So this satisfied me that I had set up the Merlins in the room about as well as could be expected. But the sub adds visceral impact and dimensionality and headroom to the presentation and a great ease & relaxation when turning up the volume. You'll never go back.
Dave