Longer forcing cones do absolutely nothing to attenuate recoil at best- if anything they increase recoil by lightening up the gun due to the incredibly small amount of metal removed in the forcing cone area.
What lengthening forcing cones does is ease the transition of shot from the larger diameter chamber to the smaller bore. This will cause less deformation of shot in the case of lead shot. Lengths over 1.5" do nothing to improve patterns though many will say otherwise. The most common reason for longer cones is the typical gun owner can see the change with the naked eye so believes something was actually done. Pattern improvements will be most noticeable with pellets larger than #4 and virtually indistinquishable with #9. Pellet hardness will also be a factor with harder pellets benefitting more than soft. Actual plating (rather than wash) and buffering will further benefit with longer forcing cones.
The other benefit is to lessen pressure spikes in the chamber area due to bridging and plain old congestion. This is more apparent with harder than lead shot but is also noticed with larger lead sizes to an extent. It can be noticed with some of the extreme velocity non-toxics to an extent. O
Felt recoil is very subjective and there is little meaningful information derived from it other than generalities. One will find much greater variability between individual shotshells in the same box than between guns as the allowable variation in velocity is roughly 45 fps from the nominal velocity giving one a spread of 90 fps in a box of shells. Shells with lower standards can have much greater variations. And that is not taking into account the vagaries found between different guns which adds uncountable differences to the equation.
Ejecta weight and speed plus gun weight determine recoil, nothing else. Newton's 3rd Law (?) can't be changed.
While you can't argue physics, spreading the recoil pulse out over a longer time period does give the impression of lighter recoil....hence the "soft shooting" term given to gas autos. Lengthening the forcing cone should help ease the transition in larger and/or harder shot. It should, theoretically, reduce the pressure spike so perceived recoil may be less. Either way I'm not concerned as this is a waterfowl gun, not a clays gun so as long as it has the typical Benelli reliability I am used to and throws a good pattern I will be happy.