It really doesn't matter what type of wall wort you use. The eGo charger is rated at an output of 420mah / hour. Which means it will take any input and convert it into what it needs. Anything larger than 420 mah output will work fine for the eGo chargers
As I understand it;
batteries are rated in mah and chargers are rated in mA.
The mA of the charger must be
less than the mah of the battery so that it doesn't overcharge the battery.
The mA of the wall adapter should be
more than the mA of the charger so that the charger can provide its full rating without overheating the wall adapter.
1.5 amp equals 1500 mA so, as BGabe said, everything is fine.
Enjoy!