I mow about 7-1/2 acres weekly. It takes about 45 minutes per acre with a Kubota B7500HST w/ R4's and rear finish mower (RFM).
This is my third tractor. The first was a gasoline 2WD gear unit w/ turfs and had a 60" belly mower (MMM). When we built our house in 1989, it was obvious the 30-some inch deck on the MTD wouldn't be something I could live with, doing 2 acres of mowing. Once I had a bigger machine, I started mowing a couple other places.
The second is a Ford 16HP diesel 4WD/HST w/ R1's and a 60" RFM.
I got the Kubota w/ a 302 FEL, and it's surprising how much use it sees. Just before coming in to see what's going on at TBN, I did about 4 acres of mowing, then slipped the loader on to load our dead refrigerator on my pickup for disposal tomorrow.
I bought a used KK 60" "brush hog" that I used one time so far. At some point this week, I'll use the FEL w/ toothbar to comb through some high brushy weeds at Mom-in-law's prior to 'hogging it. If I were planning on using the brush hog to mow over big saplings and heavy woody stuff, a smaller one would probably be better. The purpose of getting it was simply to save wear and tear on the finish mower from small rocks and stuff the kids let in the high grass.
I don't know what the HP rating of my first tractor was. It was a 154 Cub Loboy. It was OK, but it didn't have a 3-point hitch. The Ford was just a couple horses short for doing heavy grass uphill, but the Kubota walks right up places where the Ford puffed black smoke and slowed way down.
The 7500 suits me perfectly. It has sufficient power and is fairly nimble................chim