The ac adapter charges faster than usb so I would guess that the cradle/dock would also provide just power like the adapter and be faster. But someone else with a dock should be along to confirm my guess.
A charger powered by a wall transformer will usually charge faster than a USB port. The USB port specification is 5v, 500mA. Some wall chargers are rated at 700 mA or even 850mA. To make matters worse for USB charging, USB ports don't always meet the current spec. You will occasionally read a post by someone with a device that won't charge from their PC. That's the reason.
What jeffh said. My office PC has one USB port that does not charge. I changed to cradles both at home and at work. Much faster than USB and lots more convenient.
Posted from my CrackBerry at wapforums.crackberry.com
I just remembered a recent incident. Was on vacation and in a rental car. I was charging my TomTom from a car charger - some generic that I think came with a jabra car speaker. TomTom was not problem. Plugged in my Tour and a screen prompt came up - something to the effect that there was insufficient power to charge the Tour. I did not realize it was so discriminating. I don't know if it was the generic charger or the car's socket that the Tour did not like. I thought it was the same charger that we use in Europe last summer with my 8830. I have not had a chance to try in at home in my car. The rental car was a Nissan Versa with the socket down between the seats.
