I've had mixed experiences with cobblers but then I found a good one. He is not the cheapest but he is knowledgeble and honest. He fixed the frame on my Bonnie Cashin Kisslock Bag, he advised against trying to have a strap made for my caviar leather Gracie, and he repaired a tear and damage to a mahogany Patricia's Legacy. Since then he's done a lot of other things for me to repair shoes and accessories. I'm just worried that he might decide to retire!
If it's something that you can't repair yourself, then I think you need to shop around and ask questions. If the cobbler's answers are sound then just take a chance, but that's easiet to do when you didn't pay much for the item.