We had a Brillion 6 ft rotary cutter/mower/bush hog and I'm very familiar with the striping when you mow taller vegetation. We pulled it most times with a 35 hp Farmall Super H with narrow front end, plus about half the rear tires left streaks of un-mowed grass. Chopping corn stalks was one of the better things it was suited for. We mowed hay with it, our old sickle mower was shot, a new IH balanced head 9 ft trailing sickle mower was 5-figures price-wise, really hard to justify. But the Brillion worked O-K at 5 mph, would have worked better at 4 mph. A flail mower does do a nice job of chopping stuff up, but they chop everything so many times they really take a LOT of horsepower to run, or a very slow travel speed.
Had to laugh, Dad always gave me the weakest easiest to break shear bolts for the Brillion, and I'd break them, but Dad put our 100 hp 4010 Deere on the Brillion to mow some weeds and waterways. THE weak shear bolts won't even withstand engaging the pto, so he installs the Grade 8-Plus bolts he hides from me. He's going down a grass waterway in 3 ft high grass in 5th gear, 6 mph, rolling a tiny bit of coal and all of a sudden the load on the engine disappears. HE looks behind and the gearbox output shaft and blades are sitting in the grass with uncut grass starting right there. I don't know what that parts bill was, but Dad got it fixed the next day, went back out, and the 4 capscrews on the pto stub shaft worked loose and tried to shift from 540 to 1000 RPM which tore up lots of stuff in the rearend of the 4010. The 4010 went to the independent repair shop, got the "double split" and was sold and an M&W turbo installed by request of the new owner.
A 6 ft flail mower would have been nice.