[Toysrme]

Charging time is definately decreased as its drawing less power away from the onboard charger. Im charging around 5-10% every 1/2 hour while using the phone.

It would be nice if the wall-wart charger could deliver a 1500mah charging current. This would be the maximum "fast but retaining longevity" spec of the stock battery and you could completely fill the phone in 1 hour with the phone powered off to possibly 2-3 hours of light phone use. Honestly aslong as the phone was powered on you could probably give it 2000mah and itd work off the extra.
(NOT while using a usb port which could not spec wise support that current draw.)

FYI In the shipped state under heavy use the phone actually draws more power than the chargers can provide & you LOOSE battery capacity even on the charger! (haha talk about sucking!)