Understood--I've never been one for sweeping judgments. On the other hand, (as you say) an ineffective anti-epileptic can be pretty catastrophic. So I'll always be cautious about changing. What I'll want to hear is not just that the drug's supposedly active molecule is the same, but that it's been clinically demonstrated to be equally efficacious for treating seizures in multiple trials. (This is a theme that seems to be emerging in the literature: the current generic anti-seizure meds are proving less efficacious than the brand-names, and some of the latter's supposedly extraneous chemical components may actually be part of what makes them effective.)