Greg,
Curved arm bent pipe loaders have been around since the 50's or early 60's. From those that I have seen, most look like they were homemade by farmers.
In the 70's Shibura (the Japanese maker of then small Ford tractors and later Ford-New Holland and later Case-NewHolland, whom CNH has some financial interest in) played with some curved arm designs but they never really took off with the public. Those loaders were not imported here, they were all Asian market machines (although at least a couple may have found their way here via the grey market).
I don't think the curved arms started to click with the public until the tractors hoods also became curved and steeply sloped.
Commercial machines don't use curved arms, but do use the curved/sloped hoods. Commercial arms seem to be held far lower than CUT loader arms and therefore there is no advantage to curving them to increase visibility.
