You think that putting a heavy enough spring that the slide won't hit the frame will mean that your 1911 won't recoil???
There is a difference between recoil and muzzle flip. Muzzle flip is the muzzle flipping up. Recoil is the gun coming backwards.
An example of the difference is the chiappa rhino, which has the barrel underneath vs a regular revolver that weighs exactly the same. With the low bore axis, the rhino is driven straight back into your hand(s). With the high bore axis, there is more tendency to flip for the regular revolver. The recoil is exactly the same, how that recoil is presented to the shooter differs.
If you take two 1911's, one with a lightweight slide and one with a normal slide, everything else identical, there is probably more felt recoil on the one with the light slide, but there is less muzzle flip.
Because of the lowered mass, the gun is affected more by the recoil. However, the slide, essentially a giant lever acting to lift the front of the gun when it reaches the end of its travel, has less mass and is less able to lift muzzle, compared to a normal slide.
More force drives the gun backward, but there is less angular downward momentum because the slide as a fulcrum is lighter. You take a little more pounding on your hands, but keeping it from flipping is easier.
If you watch Mythbusters, it is exactly like the corked bat episode. You pick up some speed with the corked bat, but there is less energy transferred to the ball because of the reduced weight.