Seems like it'd pick up a lot of resonant frequencies from the cab? Part of the reason stands are preferred over clips for drum close mics [that and they tend to rattle a bit].
65 bucks for the audix cab grabber is insane. One thing I will throw the wishbone over these others is the fact that there is a boom instead of what pretty much looks like a fixed situation on the other 2 mentioned in this thread.
I realise you can set the other 2 somewhat how you like, but the wishbone seems to be quite a bit more flexable in mic placement.