Best only using them once it is slack and in that case then, no they don't slip.Do they have a tendency to slip inside the allan screw?
They are extremely useful. I work on motorbikes a lot and they are a godsend for some of the fixings that were designed by a sadist.
Do they have a tendency to slip inside the allan screw?
I use the Bondhus ones and I have never had any issues with them, they have a lifetime warranty anyway.
Yes unbrako are still used a lot. I know toolmakers who will only use unbrako cap-heads due to the high quality.