I just had a nice class last week and at one point my instructor said something like "people use to call it low angle and high angle. Now it's just low angle, and paddling".
That was supposed to mean that "high angle" paddling, with proper technique, is currently believed to be the more efficient and possibly less impactful way of paddling. Proper high angle paddling keeps your wrists and shoulders protected.. Maximizing torso and hip rotation, keeping the shoulders "locked". Keeping the wrists straight by loosening the grip on the top hand.. Making sure the upper arm doesn't go above horizontal (even if your hand crosses over about eye level, your elbow shouldn't go any higher than shoulder height)
I'm sure that's all possible to do with low angle paddling too, just saying I wouldn't worry about joint health just based on what kind of blade or style of paddling you pick
As for my completely unscientific and unproven opinion - if you're gonna be paddling a playboat like a zephyr, keep in mind that low angle strokes, with usually longer blades and shafts, are pretty much turning strokes all the time. It's gonna be hard enough keeping a zephyr going straight
A higher paddling angle keeps the blade closer to the hull and minimizes the turning forces from each stroke.
edit: most paddle companies make "high angle" blades with smaller surface areas. Like the Werner Shuna/Cyprus, for instance. These are quite a bit smaller than the typical white water blade, which helps with increasing cadence and reducing the impact of each stroke.