Would imagine the Kubota RTV's have different personalities like many things in life.
And will agree that the Surefoots are some great tires, and also have more carring capacity.
On our units down here, we been running the 589's and yet to have any trouble out of them. Will agree, like any other machine, if you go bigger, you will loose some power. But we have never lost power that it would not climb a hill, forward or backwards. But then again, different machines act differently. When it comes time to purchase another set, I will go down a size on the tires, but again, they will be 589's, for they serve us well.
If it was not in the winter time needing some feet that will digg and pulling. I just as happy with the OEM recreational tires. But they will not let you go really to far in the mud as we need down here. Also, the only reason we went with the 27 inchers was to get the axles up a little bit where the machine wouldn't high center and/or drag >>>>
....... two guns