Hey,
Sure the hole is a bit deeper and wider than a normal 1 3/8 slug hole and the sleeve material is not as heavy as the ball material. But as soon as you put in the inner sleeve, there should be a maximum of 1/8 oz. difference to a normal 1 3/8 slug.
I personally doubt that there is any effect on the ball motion that one could feel. But if there is one, it would make the core numbers stronger for most layouts, due to the thumb mostly being in the low RG area of the ball.