The m&p 9mm full size. I know that it is not so hard to take the safety switch out of the weapon but don't know if it would affect the function in some way.
Yes you can remove the safety without effecting to functionality of the gun. There are several YouTube videos and guides online. Just remember you will have small holes in your gun.
You can remove it with your fingers in about 5 minutes. It won't affect the function of the pistol, but it will leave two holes in the frame where the safety levers emerge. You can fill those with plugs available from Smith.