Welcome to the forum.
I know a few that have purchased and installed the "Coast Valve" that's offered on e-bay. So far, I haven't heard of any complaints or problems by installing it.
Kubota used to sell a package that would stop the abrupt stop (and actually put it on the assembly line for awhile) but most preferred the abrupt stop.
As I recall, the OEM valve can also be tweaked but thought I recall there being a potential of cavitating.
Do note that all the options that reduce that abrupt stop all do so by reducing engine braking. If you live in hilly areas, you may not want to remove that abrupt stop.
You may want to play with the OEM setup for a bit to see if you get used to it. Once you master the technique of feathering back slowly on the pedal, you can pretty much get rid of that abrupt stopping.