I am most curious as to the reason behind the no green stump burning. Is that still not a carbon neutral matter? Is it just the stink? I have been burning all manner of stuff for decades and although we don't need to pay for a permit, we apparently need to get one. Guess I just never got that memo though!
I had what most would call a HUGE stump grinder and I don't know anything about doing stumps FAST. Mine would do a six foot stump and yet you often still had to reposition it on the same stump. OF course around here, the many stones are a grinders undoing.
I just saw an ad, here in Ontario Canada. A contractor will charge $1200.00 an acre for some serious forestry equipment to completely clear land. with the addition of rock pulverizing equipment. For the abuse that this sort of equipment is subjected to, that is really not that unreasonable.