I agree with BrettS4. I have an old 7336? version (sander) of the 7424 that still works fine after at least 15 years. The 7424XP shape has a little more ergonomic shape to it. I don't think there is much difference in motor power. Use the money to buy more pads.
To be honest KEEP what you have. I have the PC7424XP but my guess there really isn't much of a difference. No need to spend the $$ to get a slightly better ergonomic DA. You probably wouldn't even notice a difference if they were side by side. Neither would I.