they are an excellent tool, they make a great " poor mans footing"
their literature purports to not even change the spine of the shaft, if repaired right in the middle.
i think the joint is an extremely strong joint, i have fixed shafts before by doing a simple 8:1 scarfe joint just behind the point , and they have held up for another pile of stumping again.
the beauty about the reparrow joint, being basically the same as the taper for fitting into your point, is that if it does fail, due to the direction of the joint, ands if the shafts splits out footing, it will probably only happen when hitting a very hard object.
I really would not anticipate an issue when releasing the arrow- and if something did happen the shards would be facing backwards- and not forwards into your bow hand.