I have a 4' Rhino. The BX does bog down a bit when I hit something ugly, like that mound from the pocket gophers that I didn't see. May be more an affect of the altitude, I'm over 7500'.
I used it all last year to maintain 3 acres of grass. It hadn't been touched for over 20 years so I thought I needed the rotary instead of a finish mower. The rotary cuts it, but it aint pretty.
This year I borrowed my neighbor's 5' RFM. Wow!! What a difference. I still hit the occasional mound, but the cut is so much cleaner and more consistent. At least as far as I can tell in a drought. Grass hasn't grown 3" this year.
Wish I'd opted for the MMM instead of the rotary when I bought it. Now the better 3/4's wont let me spend the money. Guess I gotta keep the neighbor on the good friends list.