The trick to the 5-piece is to really clean out the hole. Even a litle dust will keep them from biting.
Also, I was using 1/2" bolts, so the range is probably exponentially greater than 3/8".
The taper bolts sound cool, and, yeah, I have had some of the bolts and hangers taken, due to the ease of removal.
Jay, it's true what you say!