When a declaw procedure is done, the entire distal phalanx (digit) is removed. It does not have the same effect that removing the last digit from a human has, however. The presence of the protective sheath over the digit, rather than skin tightly adhered to the phalanx gives a natural protective closure after a declaw rather than a sensitive "stub" end. Since the cat uses its feet for walking, orientation and use of the digit is much different, as well. If the footpads aren't disturbed by the declaw procedure (they should not be) the weight distribution on the remaining portion of the toe is essentially the same. Cats tend to use their foot as a unit for manipulation of objects rather than grasping it with individual "fingers" as a human does. This makes for less disturbance in their typical lifestyle than would occur in a human with the loss of a digit.
Without being able to ask them, it is impossible to determine if cats have problems with things like phantom pain or minor discomfort chronically after declawing. These things do not appear to be a problem but there is no way to be sure.