Nah, the 2500+ XP is reveared as a good overclocker as well. It's always a choice between a Mobile or the 2500+ XP really. I almost got the 2500+ XP but then decided to go the mobile route because it's easier to get lower temps, but all in all the 2500+ XP has just as good of chance as OC'ing as the mobiles.
THe only other differences are sometimes the amount of Voltage required for certain speeds.
As you can see it takes me quite a bit of Vcore compared to 4W4K3 to achieve the same speed in GHz, BUT even though my Vcore is higher I can keep mine cooler than his because 1. Mine is a 35w chip compared to his 45w, and also I have ridiculous air cooling