I found the Tektro ONYX the worst brakes ever for cross. Had an original set on my first cross bike, tried some Kool Stop salmon pads and they didn't help much. Switched over to CR720's for around $35, front and rear with new pads and had a noticable difference in braking ability. Currently run TRPs on my race cross bike - no issues. Upgrade from the Onyx brakes and you'll get new pads to boot.
1970 Raleigh Tourist, 1972 Raleigh Sports, 1984 Miele Road Bike SS, 1985 Bianchi Nuovo Alloro, Cannondale F400, Opus Avro 29er, Jamis Sonik, Blue CXC, Bianchi San Jose, Cervelo SL-SLC, Cervelo S3 Di2 and a wife that loves me!