Thanks all for the input. After digesting all this great info, and especially after reading the Forestry Link provided by Kis, I have decided that the only tool I am going to use is my cell phone - to call a clearing contractor.
I knew using one of these tools was dangerous, but I forgot about the back strain factor. I am pretty tall and it hurts my back to even use a weed wacker. One of these heavy clearing saws would be a killer.
*****
This reminds me about the time years ago that I was going to work in a shingle mill near Forks, WA. Lots of guys at the campground where we were staying had just been hired on and were trying to get me to join in. The pay was great for the times and in a couple of months I could make enough to take us through the winter.
My buddies said to come over to the annual Loggers and Sawyers picnic that weekend and meet the guys who would hire me and show me the ropes. The picnic was great. More beer than anybody could drink, tons of good food, and everybody was real friendly.
But then I noticed that everybody over the age of about 18 had several fingers missing, some had hands and even arms gone. When the beer got flowing good, the stories started, and they couldn't have been any bloodier or gorier if they contained a Texas Chainsaw.
This was before the days of OSHA and safety was something that got in the way of work. It was common practice to pop some speed pills and work 24 hours straight. Then to get drunk to come down and crank up again for another 24 hour shift. All this with logs weighing several tons racing around on all sides and huge saws whirling only inches from your head.
I couldn't get away from there fast enough. We continued on up farther north and picked up a few bucks shucking oysters. I cut myself a couple of times with the oyster knife, but as I wiped the blood on my jeans, it felt good to feel my finger still attached, and I was really thankful that the shingle mills were a hundred miles behind us.