Be mindful some (sub)classes have abilities you might accidentally (on purpose?) duplicate. Your Vanish idea is one such thing. I think Shadow Monks do that. It doesn't make this a bad idea, but it would be poor form to make a subclass obsolete by giving their ability to anyone. If the class ability is autosucceed but your skill trick requires a roll depending on personal taste that might be enough of a difference. However, there is argument if the DC is low enough and/or your skill modifier is high enough you autosucceed anyway or only fail on a Natural 3 or less that difference is irrelevant. High level rogues don't roll below 10 either way. If this doesn't bother you at all so be it, but it is worth considering.