Dargo-Harry;
I agree with Harryup crossover comments above generally; When I had 2 subs running L/R, I liked having a higher crossover in the 100 - 120 range; Musically it helped offload the 5200s, so they performed better in midrange;

However, this requires the subs to provide part of the imageing as well, so when I went back to a single sub, I liked the 80 Hz crossover better, even at the expense of making the 5200s work a bit harder. I haven't tried the lower crossover that crion uses, but may do so later...

If you can budget 2 subs go for it, but these things are so room and listening dependent that 1 at a time may be a more pragmatic approach.

ken