i purchased a 3520 ehydro and I'm very pleased. the 42320 should be the same just bigger and more hp. As tranny's go I was not convinced I wanted the hydro. I rented one and used it aerate 75k ft2. You can't match or beat the efficiency of this tranny. It's great for situations where you need to change direction a lot. I use mine with a back blade for snow removal in a HOA with 120 drive ways. No telling how many forward reverse motions I did in the last storm.
For long pulls under load I would rather have a gear type tranny. Ag applications are the first thing to come to mind. I tried the power reverser and I thought it was a good set up. In fact I was ready to get it just to save some money......but I tried the hydro and decided the increased production for my applications would pay for itself. I feel it has.
I like the kubota too. Excellent tractor. For me the pedal set up on the deere was a better design.