You're right on, Bird. The rear roller on the flail that supports the unit, is quite close to the flails, like an anti-scalp roller on a rotary mower. With the flail, it is very unlikely to throw derbis when hit, and safer to use around people. There are heavy duty flails, like orchard flails, that have heavy duty knives that chop tree limbs. Another feature about flails, it discharges cut grass over the width of the unit, and does not windrow like a rotary can. A while back, I had a Ford 5' flail, and it used it to mow 5 acres around the house, and it produced a very good cut. I'm still waiting for my JD 25A to be delivered, the way the weather is going, that will have to wait for next summer.
Paul