Someone with similar requirements reading this thread in the future might be interested in what I chose for a solution. It'a bit over a year since I asked for advice for mowing on sloped, rough (not lawn smooth) terrain.
The North American distributor for the German AS-Motor AS-940 Sherpa ride-on mower never did bring a unit into Vancouver for a demo last summer as they stated they would do. They also could not answer some basic questions such as how to get warranty repairs done if there were no dealers or service centres in Canada, where I live now. Even though this mower seemed like a good technical solution and was a fraction of the cost of the other equipment that I was evaluating, it didn't seem practical. As I wrote in a message to AS-Motor in Germany, North American buyers want to know that there will be someone to support and service equipment that they purchase from overseas. The contact address for AS-Motor in the USA is a residential apartment building in the middle of a golf course in West Palm Beach, Florida, so that doesn't give the impression of a service/support center with a warehouse full of parts and with guys with wrenches in their hands who can help to solve a problem. There was also some doubt about how steep a slope this machine could handle. One of the marketing videos from the manufacturer that I referenced earlier showed an AS-940 Sherpa going up and down an (estimated) 40 degree slope, but the operating manual doesn't specifically state what slope steepness the machine can safely mow in those directions. That's odd, because they do state that is can do 23 degrees sideways, so I'd estimate that it can safely handle 30 degrees mowing straight up or down.
I was fortunate to be in a position to be able to purchase my second choice of mowing solution, the Ventrac 4500 with dual wheels and tough cut mower (which the manufacturer, Venture Products, says can mow 30 degrees up/down and sideways). I made that purchase this spring. With its 68 inch cutting width it has cut my mowing time to about a third of what it took me previously. The physical effort is miniscule compared to wrestling that 300 lb walk-behind DR brush cutter around. Onlookers are surprised when they see the machine mowing up and down the (up to) 30 degree slopes on our property. I have tried mowing across the 30 degree slope as a test, just because the manufacturer says that it can do this. The tractor was stable on the slope, but I wasn't stable in the seat. Some sort of 5-point racing harness would be useful to take advantage of the machine's full capabilities! The quality of everything that I've looked at on this well engineered machine is fantastic and the support from the manufacturer is excellent. I think that if I take care of it that I'll have few problems with this absolutely top notch piece of equipment. It's a pleasure to own and operate.
It's probably evident from my earlier posts that I research things, so I knew that while Venture Products says the Ventrac 4500P can handle 30 degree slopes, the engine manufacturer (Kawasaki) shows in their operating manual (provided with the Ventrac but also available online), that the safe operating limit is 25 degrees. I knew about this discrepancy before I made my purchase, but I reasoned that on my property the tractor wouldn't be at 30 degrees for more than 30 seconds so I was fairly confident that engine lubrication wouldn't be an issue regardless of what Kawasaki wrote. When I queried Venture Products about the discrepancy, they responded with:
"Ventrac IS certified for 30 degree slope operation in the 4500P. In fact, part of our certification process includes sending a unit to Kawasaki for testing to ensure our tractor (with their engine) meets the 30 degree number that we claim. It is my understanding that the reason the Kawasaki engine manual only lists 25 degrees is simply because Kawasaki has not yet gotten around to updating their manual. It's possible that other non-Ventrac machines that utilize that engine weren't safe to be operated above 25 degrees before. But then the Ventrac came along and changed that, requiring a manual change that they just haven't yet made."
...And I responded in part with this:
"If I was a contractor and wanted to be sure that I could mow all day long at a 30 degree slope, though, I'd want more of an assurance that the engine could handle this. Since Kawasaki has tested the 4500P, they would have given Ventrac some documentation that says something along the lines of "We warrant that our FD851D engine, when operated in the Ventrac 4500P tractor can run continuously at slopes of an angle of 30 degrees.". It would be beneficial for that documentation to be available to people questioning the contradiction in the two manuals. Without it, prudent potential buyers will assume that 25 degrees is the safe limit to not damage the engine, and that may cause some people to not buy the 4500P."
Shortly after I made my purchase, the government of the USA imposed tariffs on steel imported from Canada. As background, in 2017 Canada exported to the USA 5.8-6.0 million metric tons (mmt) of steel and imported 4.8 mmt of steel from the USA, plus a whole bunch of manufactured products that use steel, like Ventrac tractors and mowers. In response the Canadian government has imposed tariffs on a wide range of goods coming into Canada from the United States. In addition to the 4.8 mmt of products directly produced by steel mills, the tariffs apply to a range of manufactured goods including one tariff targeted at "Mowers for lawns, parks or sports-grounds: Powered, with the cutting device rotating in a horizontal plane". I'm an engineer, not a lawyer, but I'll guess that this tariff will apply to all of the Ventrac mowers, if not the Ventrac tractor itself. So the already expensive Ventrac products will get more costly, in Canada (if this tariff applies) and in the USA and anywhere that Venture Products exports to, because steel prices in the USA have increased since the tariff imposition. This steel tariff was ostensibly targeted at Chinese overproduction (China accounts for over half of world steel production but only 2% of steel imports to the USA). Instead it is really hitting the country allies of the USA, American consumers (the prices for cars and trucks and washing machines and everything else made of steel will all likely increase) and American workers at manufacturing companies that produce products using steel.
