I have this attachment for my older Bernina. I never use it. I recall that it is a PIA, but others may like it. I remember getting lots of funny wrinkles going around curves.If you want to spend the money, ask the dealer for a demo and a chance to try theirs.
I just rewatched the Bernina videos on the attachment. A couple of things to note: Nina always uses TruE bias.
When was the last time you cut that? The purse handle was cool, but I'm wondering how much fabric that took.
Neither video shows a mitered corner...because it's about impossible to do neatly with this attachment.
Also, did you here them say that you need a #94 foot? One may wonder if that's included in the cost of the binder.
I enjoy the final hand stitching on a quilt for attaching the binding. Having said that, Judy Laquidara has a video tutorial on attaching bias binding totally by machine. I did this on a wall-hanging recently & had to fix two of the mitered corners, but am pleased, as this is no where near a show quilt. Wow, is it fast.
See her great tutorials at http://www.patchworktimes.com/category/tutorials/
Take the time to explore her posts. She has lots of great information and lots of free patterns.