I just received my new flail mower from Betst, and it seems like a pretty good deal. $1000 for a 64" mower, and another $200 for the heavier brush blade kit. Betst is in Oregon, and I'm in Washington, so it arrived in a couple of days. Freight was included in the price, too.
It took about an hour to uncrate it and put it together, and I was able to give it a fairly limited trial yesteday. Western Washington has lots of huckleberry and salal, and the mower goes through that easily enough. My property is uneven, with lots of stumps and such, so a flail seemed like a better choice than a rotary mower for me. A bonus is that it's not as long as a rotary mower, so it leaves the tractor just a bit more maneuverable.
The mower has a two-year warranty, too, which helped me make my decision.