It wouldn't be effective in the slightest. They have difficulty as it is managing DHS.
Improved models of police work will be created and adopted by certain key cities or communities and it will spread from there.
There is simply no reason to argue that federal control is necessary.
"We all of us know down here that politics is a tough game. And I don't think there's any point in being Irish if you don't know that the world is going to break your heart eventually."-Daniel Patrick Moynihan, December 5, 1963
“looking with fondness towards a reconciliation with Great Britain…I…would rather be dependent on Great Britain, properly limited, than with any other nation on earth or on no nation”. Thomas Jefferson; August 25 1775
Last time I checked there already existed quite a number of federal police forces in the US: FBI, DEA, Secret Service, TSA, etc. Having federal police forces to deal with federal crimes is logical. Just As it is logical for States to have police forces to deal with State crime and local autorities to have police forces to deal with local crime. I see no need to change this.