I'd say there is a huge difference in the actual use of the curved loaders versus the straight/dogleg loader arms. And people who have experience on both types will typically tell you that you get used to either one, but most seem to prefer the curved arms after using both. I happen to have both, I can tell you that I can get work done faster with the curved arms, the visiblity is vastly improved. Much of the advantage of the curved arms comes from not just the curved arms, but also the curved & sloped hoods of the tractors. They work together as a system to improve the visibility so much that you can actually see your work, that seems like a small thing but in actual use I have found it to be a time saver (and time/labor savings is why I own tractors).
The photo comparision may not be perfect, but it illustrates the point. It should be pointed out that the Kubota/NH have very similar FEL capacities. The Kubota blocks your view to signifcantly farther out, you also can't see the bucket corners on the Kubota. The Kubota grill guard blocks the view to just under 7' in front of the cutting edge of the bucket. On the NH, the ground is visible at just under 3' in front of the bucket. The photo of the green tractor (photo 3) is a Montana. This is not a good comparison because the bucket is NOT flat on the ground, however the loader arms really bock the view because they are mounted much higher so you lose much of the sight advantage with the Montana. I also don't like the plumbing on the Montana, I much prefer rigid pipe over hose on a loader, costs more to pipe it but never has to be replaced and is harder to damage (in my experience).
I'd also point out that not all curved arm/sloped hood tractors are created equal. Some (like Deere, Montana & Kioti) don't have hoods that curve down as steeply or curve side-to-side as New Holland or Case which I believe offers the best view. Kioti is probably the next best hood shape, Montana probably the most traditional of the hood shapes and offers less of a view. Deere offers a good view over the hoods of their new tractors (good not great) but their loader arms are 2 part curved arms and offer a more obstructed view.