There's been quite a bit of discussion on the DR and other field mowers. Do a "SEARCH" and it should turn up the information you need.
I've had one for years, one of the older versions without pneumatic tires and a reverse gear. It still works very well for cutting around the lake at the farm but they are a lot harder work to use than the advertising would have you believe. That shows them mowing down 1" saplings and that it WILL do. What it doesn't show is that you have to wade and stumble through all the trash it leaves behind while tripping over the 2" high stobs it leaves sticking up. That's where the hard work comes in. For grass and weeds in small, hard to get to areas, it works as well as anything else and better than most but if the area is larger and overgrown with saplings be prepared for a workout.
It's no substitute for a CUT and a bush hog.