Here's my review of the 800. It's called The Might from Dwight:

https://www.axiomaudio.com/reviews/index/list/product/64/

Ian has tuned the 600 to reach down as low as the 800 but it won't go as loud. The specs page does not reflect this for the 600 I don't think. Ian uses 600s in his set-up.

House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated