The 850 is not as powerful in the ANR realm, but has several advantages...
Relatively Cheap
No Batteries (with most ANR's, when your batteries die you go lost comms)
Light and Comfortable
Small (fits easily in your flight case)
It has enough active and passive noise reduction for the CRJ, but an ERJ or turboprop might be a different story. My TELEXs have all proven indestructible...I lose them before they break.