I have beastmount and it survived at least 15 sessions.. even one when the kite popped the strut after the tomahawking..
maybe I am lucky.. but I usually use it in "melow" conditions.. Never want anything on my lines when I am crazy powered...
I also remember hearing someone complaining about one.. but I really don't see how it can break if placed in the right place on the lines and w/o major crashes...
If it changes geometry of the lines - that's a different story, obviously..
In any case, why not just make a mount out of a wire hanger or a piece of electrical wire and some duct/electric tape?
it may not look as cool, but it wont break (and that may be a bad thing if you find yourself trying to flag a tangled line kite in crazy conditions..
I used one in the picture before I got beastmount as a gift..
they both work the same and once the beastmount breaks - I am going back to the wire