If I was that worried about not having a safety, I'd carry a gun with a thumb safety. The beauty of the Glock is not having to disengage a manual safety in order to fire the gun.
This device is just another thing to fumble with. It's a solution searching for a problem. It's a nice design but in my view it's unnecessary.
The sad thing is there are people that will buy it simply because somebody is selling it and they must have every accessory on the market. Practical or not.
No thanks. Keeping my finger off of the trigger works fine for me.