I tried several of those and the magnets were all so bad that they couldn't even support the weight of the cable itself and would lead to fraction-of-a-second disconnects, which in one case led the mac to disable charging on the port (temporarily. the apple store fixed it but I don't know how).
At this point I don't think the reward is worth the risk. But I am glad to hear that at least some of them aren't terrible.
I use it to connect to the dock on my desk, so the cable weight wasn’t an issue, but I can see how the weight of the cable pulling down would disconnect the magnetic connector.
At this point I don't think the reward is worth the risk. But I am glad to hear that at least some of them aren't terrible.