>>1036338>>1036364>A braze-on is much easier to adjust than a clamp-on.lolwut
Okay sure, making a slight adjustment to a braze-on derailer is slightly easier than with a clamp on derailer but it's not a significant difference - with one a height adjustment takes 20 seconds, the other takes 40 seconds.
To answer your original question: no, it might make sense (cheaper) to buy the adaptor if you already owned a braze-on FD you'd like to use, but otherwise you're just adding needless cost and complexity for no real additional benefit versus buying an ordinary clamp-on FD.
