Thanks for commenting on the mount and for your feedback on the design.
I must reassure you; both the material and design are particularly robust. You shouldn't fear breaking a tab off when releasing your Garmin Varia.
Feedback in the initial design phase was the number one priority was that the device was safe and secure. So the mount has been purposely designed to have a strong grip when your Varia is attached. That way, unlike other designs I've come across, there's no chance of you loosing it.
Because the mount is quite small it's hard to remove the first couple of times if you're just holding the mount. Best to have it attached to a saddle and use the leverage of your Garmin Varia to remove it.
Regarding the fit of the GoPro lug, all the different type's I've tried offer a good fit. Obviously I cant control what tolerances other generic mounts are designed to. But if you drop me a direct message I'm happy to tweak the design and send you another mount to try that has a tighter fit.
Feel free to get in contact if you have any more queries or questions.