Increased movement speed is always strong in shooters, and that’s no different in MW3. Combine that extra speed with a mobile weapon like an SMG, and you become an absolute nightmare to deal with.
Lightweight boots are strong, but their usefulness varies massively depending on your weapon and the map.
Unfortunately, I can’t see a massive benefit to faster and quieter swimming, which holds the Lightweight boots back.
Boots have Perks that specifically improve your movement and swimming, as well as how loud and maneuverable you are. Every Vest (except the Gunner Vest) allows you to pick one pair of Boots from the following:
Lightweight Boots
Increases movement and swim speed. Reduces noise while swimming.
Climbing Boots
Increased climbing and mantling speed. Reduces fall damage.
Running Sneakers
Increases Tac Sprint duration and reduces refresh time.
Tactical Pads
Increases slide distance and allows for aiming down sights while sliding. Increases stance transition speeds and crouched movement speed.
Stalker Boots
Increased strafe and ADS movement speed.
Covert Sneakers
Eliminates footstep sounds.