If you plot a recoil force/time curve, the total energy under the curve will be the same for fast vs. slow powder that produces the same velocity.

Since the peak pressures are different, acceleration of the projectile will differ if internal ballistics were measured. That's straight forward pressure acting on the base of the bullet to accelerate it. If you have pressure values and bullet base area and weight, you can calculate the force applied to the base of the bullet. If you believe Issac, there is a corresponding reaction of the gun, with equal force pushing the gun in the opposite direction.

The physics say that there will be a higher peak recoil force for a higher peak pressure, all other things being equal. Can someone feel it? I'm guessing yes, if there is enough pressure difference. There's a lot of anecdotal testimony to support that people can feel differences. The gas auto is an example of approximately the same total energy under the gun recoil force/time curve, but a lower peak force at the butt, while much of the higher force is spread over a longer time. People definitely feel a difference with autos, yet the payload travels at the same velocity, for all practical purposes.

The word "recoil" is not definitive enough to understand if someone using it is talking about total energy of the gun against the shoulder or peak force of the gun against the shoulder.