It works fine on a superbike, and was developed with Colin Edwards in MotoGP. You can't use the large off road versions on a superbike, but the STX RR is not noticable in a tuck on the panigale.
I guess the full race airbags systems on the race suits are even better than a brace, but for the moment they are a bit too expensive for me, so I found the brace a worthwhile addition to the safety gear package to use while on the bike.
Some reviews:
Product Review: Leatt STX-RR Neck Brace | Riding in the Zone
CW Evaluation: Leatt STX RR- Neck Protection For Sportbike Riders
http://www.useimagine.com/ItemImages/417/Ready/8870/OTOR-STX RR Colin.pdf
Colin never won though, just saying.