My Conn Ferr rack looks more shallow than yours and I definately notice road noise. I had this on a different XJ for two years and just moved it to my red Cherokee. Same noise on both (duh). Driving the Jeep without the rack is much more pleasant, but it is a worthy trade off.
It is loud enough to notice. Not sure the actual decibel level, but it is like a loud, continuous, low rumbling fart after a particularly satisfying trip to the local buffet.
By the way, I have had three separate racks on four different Jeeps. Liberty and Thule = loud. Grand Cherokee and BMG rack = loud. Cherokee and Conn Ferr = loud.