any other arguments that might NOT fail?
Depends on a number of factors. Was there video? Had you left the store? Was the merchandise concealed? Who is the judge? Call an attorney in your jurisdiction for more specific answers. There are a number of things to consider on a theft charge. You may be able to get a deferred sentence. Or with the right judge and the right facts, you may be able to make the argument that the store employees are nothing more than agents of the police. Particularly if they are employed solely for the purpose of theft apprehension and have had specialized training. You may also want to consider that this time of year many of the employees are seasonal empires and may not be in court three months from now when they are working elsewhere.