In the really soft, fine grain sand, it really doesn't matter much, the digging is easy with little effort either way, the scoop washes out quickly which reduces the weight at the end of the stick,.....very little fatigue is experienced.
On the other hand, hard sand, or a sand and gravel mix, perhaps clay, these conditions can present an entirely different situation. It takes more force to penetrate, takes more energy to remove and lift, so now leverage suddenly becomes a factor. Without a doubt the old Miller style looped handles provided the best of both worlds, they provided great leverage and torque and though the bucket sat at a 90 degree the offset, or stepped back loop, allowed for little bending over even in the firmest conditions. This looped design also allowed you a great deal of leverage when removing the bucket and the position of the front shaft of the loop allowed you to easily slide your hand nearer a full/loaded bucket for better balancing. Ah, but the Miller is no more and today's manufacturers just haven't incorporated the concept into their designs, probably due to cost factors, but they should. If a guy will spend $1500 to $2000 or more on a machine he'll certainly dump $300 - $350 into a top of the line scoop. I know I would.
So I think "conditions" is a big factor in determining which handle design best suits the hunter. I have a couple of different scoops, 90's/45's/20's, big and smaller buckets, just for this reason. Nothing worse then the scoop that's wearing you out.