wjt3 has me thinking. I currently have a pair of GR Research dual servo 12" OB subs and a pair of Spatial Audio M3TM speakers, with a pair of Spatial's X5 on order - arriving hopefully in a month or so. When they show it will be easy to set the M3TMs as another pair of OB subs. Maybe do a maxi swarm set-up. Hmmmm.....
With the X5, you might not need any subs.
And doing a swarm with OB subs is a bad idea. A swarm works because it excites the maximum number of room modes, while OBs work by minimizing the number of room modes. So a swarm is best with box subs.
You could sell the speakers and subs and buy some extra amps, I bet the X5 is awesome to roll in amps with different presentations. I know I do that in my systems, I have 4 tube amps and 1 SS amp that I rotate through, it's quite fun.