Weird IMO, I got neighbors use 92 HP with bat wings and they do just fine.
Keep in mind I'm not clearing fields, I'm maintaining fields.
Shopping for a 12' or 15' bat wing now for use with my M9960. It will handle it at reasonable speed when not in EPTO.
All of my areas have been mowed for decades so I mow only grass. That said, heavy grass cuts much harder than tall weeds/brush, etc., especially if one cuts closely as I do.
I engage EPTO onn the M9960 with the 7' cutter. Doing so results in 540 PTO RPM at about 1,700 engine RPM, saving wear and tear and fuel in the process. That said, the engine is making no where near 90 PTO HP at 1,700 RPM. The 7' cutter is all the 9960 wants when in EPTO.
More significantly, the 6' cutter is all the 53 PTO HP L6060 wants much of the time at about 2,400 engine RPM, which is 540 PTO RPM. The L6060 does not have EPTO.
Unlike most, I keep my rotary cutter blades sharp like a lawn mower in order to improve cut quality and reduce HP requirement and fuel consumption. I also try to mow as fast as the mowers cut well and terrain permits. If engaged, the stall guard on the 6060 routinely slows ground speed to prevent bogging the engine.
Again, it depends upon what you plan to cut and how fast you plan to cut it.
From experience, I can say unequivocally that my L6060 will not touch an 8' mower in my conditions except at quite low ground speed. Even then, it is too light to lift one in anything other than absolutely ideal (level ground) conditions. I currently use 4 front weights with my approximately 1,200 Lb. BB720X.
SDT