Jim, to answer your question "where does this come from" I have a very simple answer to that, USE, personal use. My experience only refers to the Grande L, I know nothing about B tractors from Kubota other then what I read here. Since I am interested only in the largest HST tractors, it restricts me to the JD 4600, TC45 or Kubota
L4610. There is a test you can use to test a HST that helps understand the differences.
1. With the tractor at the lowest possible RPM, place the tractor in the highest possible transmission speed. Now depress the hydrostatic pedal as quickly and forcefully as you can to the floor. Observation, Kubota's HST will not jerk, jump, buck or stall but safely, very smoothly rolls forward or reverse at operators control.
2. With the tractor at the highest RPM, place the tractor in the highest transmission speed. Now feather the HST pedal, easily and lightly, just a fraction of an inch, just a little toe pressure. Observation, the Kubota Grande L's will without fighting you with back pressure, load noise levels and whinning safely begin to roll forward or reverse while in full control. Other colors have no where near the absolute 100%, inch by inch control the Kubota offers.
The load test pretty much requires a loader and big piles of dirt that will stop the tractor. It is simple and simply requies that you plow into the dirt. The Kubota swasher plate hydro servo HST still requires a consistent foot pressure to maintain forward momentum or pressure, about 7lbs, pedal pressure on the others goes up, way up.
This is not an indictment of the NH or JD products at all, they have merits of their own, others who own them can tell us about them. Your experience with the TC18 affords you the ability to lend opinnions well in the sub compact tractor arena, at least 60 hrs worth plus all the details you poured over before you purchased it. I should have mentioned to Sam that he try the TC45 as it has perhaps a better fit for him because of his larger size. The open area of the TC45 is nice and the swivel seat absolutely great. Its a nice machine and deserves its own accolades, but I thought I would leave it up to Hawgee or James who have more familiarty with it. Rat...