1987 I bought an old tractor, then a Bush Hog 105. My land included two small "meadows" totaling ten acres. 1946 the land stopped being used for cattle. By 1967 it was overgrown with 8" cherry trees. those trees were cut down & left there. By 1987 when I bought it each stump had sprouted 8 to ten 4" diameter suckers & they each lay on the ground a few feet before going vertical. They averaged 25' tall. Between the cherry was a jungle of Honeysuckle bushes. It was so dense it wasn't possible to walk through.
Clearing this was an overwhelming job for old equipment. I spent the summer every weekend in a rotation between mowing & repairing. My beater Bush Hog now has as much weld filler as original steel! I've replaced main shaft on the gearbox twice, countless blades, several oil seals, & welded/reinforced multiple breaks. Twisted the PTO shaft inside the tractor transmission, & broke it another time.
Advice is you want to select your hog to match the job. If you are only going to mow weeds & grass, a light duty mower will do.
I prefer shear pins over a slip clutch. Machine can take a severe beating whaling a rock at 1000 RPM blade speed.
I'd insist on a stump jumper, a bowl shaped device blades are attached to. It helps get over a stump or rock & helps (somewhat) to keep stuff from winding around the blade shaft & ruining your gearbox oil seal.