This is a good point, to add to what I say on previous page to weaver < If my calculations are correct & they do appear to be without me using a laser for start/stop, then the 3100 being lets say a 12.8 mph mower, would be very close to or right on a 14 mph mower with 26 " tires. Since you cant utilise the true 15.8 and you say your more often than not using 14mph range, then this would bring the 3100 so close to a fast enough mower for you also. Would that be right. I would go as far as to say you would complete your mowing just as quickly taking into account the entire property, because your rough sections you will be able to cut twice as quickly. I don't know what percentage of your property you find yourself backing off even a little due to even small bumps, but if you do back of for them on the SZ you wouldn't do that on the Ferris as you know. So I'm betting you would complete your property in the same time frame.