I have a single ML BalenceForce 210 in a substantially bigger room (20x24) than you do and it does the job with my ML CLXs. It might be nice to have a pair for stereo bass, like I had with my Entecs, but it eats up floor space I need.
The Ml BF subs have the advantage of being able to use a ML supplied crossover for your 13As. There are two, one if you want to run the 13As full range, and another if you want to roll them off in the bass. I run my CLXs full range. Then, with the PBK kit and Anthem software, you can create a custom BF output profile that can give you a much flatter in-room bass response. I can’t imagine using a sub that can’t do this. The before and after is night and day.
I don’t know much about their new subs, maybe they do all this for less money. I would call them and also look on the ML forum.