Any flow specialist worth his beans will tell you that any tubulance in the actual port is just using energy and slowing flow, introducing a chaos factor as that area will react very differently at differing rpm and velocities.
All effective swirl is created with port entry angle, port configuration and valve seat setup.
And when you come to the age old argument of finish, i find it particuarly poinltess on modern engines as the injectors basically sit 3" from the back of the valve head. And since fuel is injected before the valve is even remotely opened it wont matter what your surface is like as it pools behind the valve. On old cars where the injectors were miles up the inlet tract or a carb was used, it was important to keep suspension through all the bends and pressure drops you encounter. It all depends where the point of fuel is introduced. On bodies you need to keep suspension as the injectors are upstream by a decent amount, and moreso on racing vehicles which have outboard injectors.
As for that rifling thing, IMO it kills any nuance of boundary layer and generates a centrifugal force to spin out fuel, along with the rifling which adds 'drains' if you will to hold fuel and the sharp edges will actively remove any nice flow pattern you create.
To me though, its a matter of flow quality over quantity.