Really, the factotum isn't so much a dabbler "cover all the bases" class, as it is an amazingly good skillmonkey that also dabbles in a few other things. None of the other things they do come anywhere close to their skillmonkeying. In fact, if I were to ban the class, it'd be because they're better at skills than the rogue is, who's supposed to be the best at skills, and doesn't really have anything else worthwhile.