I have the 72mmm, my speed has been limited to the bumpiness of the ground, before I got the kubota I was using a husqvarna 2654, 26hp 54 inch deck riding mower and i had some spots that I could barely go slow enough to not bog it down. Haven't had to worry about that since the kubota. Used to take between 3-5 hours to mow my place depending on how long the grass was, now it takes less time and I mow my dad's 1.25 acre too. I mow every 1-2 weeks, so it never gets real long. Wish I had more experience with other machines to be able to give a more informed opinion, but I am happy with the 2650. Works well for what I need.