My opinion : a front-mount, whether with carbide hammers or cutting knives, is not the solution to all problems. Where there's a lot of rocks, the excavator is probably the best option in terms of cost of operation (better visibility, better control on what the head's doing).
And again, in my opinion, if you look for a brushcutter that's also a rock crusher, you'll probably end up with a tool that is under-productive at each job.
Palmettobrush, regarding the off-brand tools, considering the enormous amount of money we've spent on developing the technology, we're having our patents lawyers considering legal actions against businesses copying the general design of our teeth. Patent infringement is no small deal.
If you want to see the technology continue to evolve, buy your teeth from DENIS CIMAF. Not from people who live on everyone else's ideas...