I haven't used them, but have talked to the folks at Brian's Archery in Rochester NH that use the exlusively and sell them (so take it with a possible grain of salt), they have taken elk and bear and deer with them and swear by the accuracy and blood trails. A friend used one on a doe and it opened up a HUGE hole and left a great blood trail.

They are new and had delivery troubles for this fall so direct experience is going to be a bit rare, but the accuracy of them is unbelievable.

--Bob