Cribbing is a very difficult problem.
Recent studied by Cornell Veterinary School also agree that cribbing is a disorder that was almost non existant in wild horses. They also say that their studies indicate that ulcers or digestive disorders are unlikely to be the cause. They treated cribbing horses with Virginiamycyn and found they all continued to crib.
I have read that treating for ulcers has worked also but it was hearsay so I can't be sure one way or the other.
Cornell does seem to believe that horses fed highly concentrated feeds have a predisposition to cribbing.
Free choice hay and 24 /7 turnout seems to be best for cribbers.
Cornell also believes it is hereditary. (Studies were done in 2009)
Equine Ink Cribbing:Presumed Causes is where I read the article about Cornells research. Someone else may have newer research info.
One thing I do agree tho is that it is an obsessive compulsive disorder that you are unlikely to cure, it does not effect their health, (other than wear on teeth which one should expect) when they are cared for properly, and it is not true that cribbers are hard to keep weight on.