471 are they used if not they've been on the lot a while they have been replaced by the 500 series. I would not compare the 471 to a m9000 Kubota The 9000 is a higher horspower tractor and the 400/500 series are also utility tractors (reason they are cheaper). To downgrade from a 4230 to a 471 is a big step down in horsepower and weight. If I was looking at a Massey Id look for a used 4355 or a new 5455 they have 85 pto horsepower, good weight, and are heavier built than the utility 400/500 series.
Always remember to compare apples to apples, because Deere and Massey both have utility lines that are not the same as their other models with the same horspower.
My experiance with the Kubotas (2 M9000) small PTO clutch packs and light weight, really need a counter weight when you have large rolls on the front end loader, and the temps seem to run a little higher than the other tractors, but man are they quite.
My 5455 Massey cab/4wd no complaints yet pulls hard handles my 505m Vermeer like a dream. The 5455 was a upgrade from a 2wd 4355.
And what ever you do don't get rid of your old 4230 those old 4000 series JDs are the best tractors JD ever made.