If by "safe" do you mean the safety is very positive (will not go on and off easily / accidently ) - yes it is very safe - I'm used to shooting 1911's and the safety works just like a 1911.
It comes with a medium grip module - I bought a large FDE grip module (dremeled out the slot for the safety) and it worked fine.
The grip modules that have the slot for the safety - do not work well for grip modules for non-safety P320 - because the empty safety slot allows a pin that is there on the non-safety model to vibrate out of place.
I hope this helps - I love the thumb safety model because I train and like the extra level of safety.
It comes with a medium grip module - I bought a large FDE grip module (dremeled out the slot for the safety) and it worked fine.
The grip modules that have the slot for the safety - do not work well for grip modules for non-safety P320 - because the empty safety slot allows a pin that is there on the non-safety model to vibrate out of place.
I hope this helps - I love the thumb safety model because I train and like the extra level of safety.