Jim wrote:

Looking to purchase a consumer grade lawn tractor. My 18 year old Sears
(Murry) riding mower has manually selected gears. Many of the new
machines boast hydrostatic transmissions. Are these really any better?
Are they as durable as regular gears?

Yes and no. Hydrostatic transmissions are great for the precise speed
control they give you, but they are have a down side of being far more
expensive to repair than a manual gear box and much easier to damage
with improper maintenance. For a commercial landscaping service, the
zero turn dual hydrostat units save more time than they eat in extra
maintenance, so they make sense. For home use I'd stick with a manual
gearbox.