ME...

if you fly to race or fun your thought is ok
if you fly for results (filming or photo)... they're quite the same as seen the camera and lightbridge are the same one
Well, I'm afraid the situation is really the opposite.
If you would like to have a drone just for some fast flying, with sudden turns and tricks up in the air, Phantom 3 is a better choice.
Lighter, easier and faster setup, easier to carry, easier & cheaper repairs (fast flying increases the chances to crash considerably) easier to manoeuvre in tight spaces etc.
But if your piece of cake is aerial photography/filming, let's just say Phantom 3 is compared to Inspire 1 like Danny de Vito vs Arnold.
They used to be twins, same same, but different.
Once you experience the dual operator mode and the 360 degrees control of the Inspire's gimbal, I'm sure you will change your opinions in this matter.
Also think about aerial works in unfriendly weather (it happens most of the time), trust me, in rough winds Inspire is the Arnold of drones.
Bottom line Luca, I think the best way to see the big differences between these two products is to test them in the same location, for a serious aerial work.
Guess you will change your opinion, fast.