Good Morning,
These units are powered by a 3 cylinder Kubota GAS engine. They were built in the '90s. I own a '93 model with a 60" deck and 700 hours.
It is a strong running unit that mows about 3 acres (or more) every week. I bought mine at auction and it had fuel problems. The previous owner did not figure it out. He told me when it start running rough to change the fuel filter or it may need a carburetor. It turned out, the finish on the fuel level sending unit rod had deteriorated and was stopping up the filter. Disassembly and cleaning the tank and rod fixed that problem. The other thing to watch is overheating. The radiator, interior screen and external screen openings are fine and trash will build up on faster than expected. Finally, they use about 50% more fuel than a diesel.
Your question about the hill and dew is interesting. The unit will pull hills without issue. The tires may need to be replaced depending on their condition. Mine have gotten hard with time and since the unit is two wheel drive, they tend to spin on wet grass. I replaced the tires on my
B7100 last year and that made a tremendous improvement in traction, so I figure it would do the same with the mower.
In my opinion, if the unit is not abused and the price is acceptable, I would buy another one.
Hope this is helpful and you enjoy the mower.