I've used various hair clips (including bobbie pins) over the years and have liked them all. I always knew that eventually they would "stretch' and need replaced but that was ok with me. I still use the hair clips at times, but now I use Wonder Clips the most. I have found they work very well for me on curved bindings as well as straight ones and I really like how I can secure the mitered corners well with them.
I have discovered another way to use the Wonder Clips. I teach a fairly large number of beginner classes, which often include young students (ages 7-15). It is not uncommon for these students to have difficulty with pinning so I show them how to use the Wonder Clips in place of pins. It works , well, WONDERS. :-) There are no more stuck fingers and bloody dots on fabric! Happily, the piecing is done quite well, especially intersections, and everyone is happy. They all eventually move on to using pins, but this sure has helped.