I have not had any issues with the unit charging off non-Motorola chargers. I have successfully used a Blackberry charger and a generic 12 volt to dual USB charger, in my car ,with no issues.

 

Not sure where you got that quote but it is false. I've tried many different micro chargers and have not had any problems.

 

I got my Atrix 2 weeks ago and have had problems charging it from both my Mac's, an iMac and a MacBook Pro. The wall charger included say's the output is 5.1 volts. I also got a car charger in a package deal from CostCo and it works fine. I did some experimenting and found that it will charge from both my PC's, one tower and a laptop and from both my iPhone AC adapters but not from another Motorola charger for my Bluetooth Jawbone that say's 5.0 volts.
I tried connecting it to my MBPro via a powered USB hub and it would still not charge. I checked the voltage from this AC adapter and it say's 5.0 volts.
It seams that the charging circuit is requiring 5.1 volts and is sensitive enough to reject anything as low as 5.0 volts.
Hope this helps someone else...

 

Wrong. I've been using a 5v 550mA charger since day one and it works fine. It's the charger that came with my Motorola BT S305 stereo headset.

 

The only problem I had with charging my Atrix is when it went completely dead. I couldn't use any USB (Laptop, XBOX, PS3, etc.) port to charge it. The output wasn't strong enough to kick it off. Had to use the wall charger to "Kick Start" the battery.

 

That's because USB ports on computers/consoles/etc have an output of 500mA. Most micro usb or AC->USB adapters are 1A, and the atrix has a 900mA battery. Because of the "juice" that the battery needs, a 500mA USB port is not going to charge the phone, but will keep the phone from dying [as fast]. I recommend a 2A charger (wall &| car) to charge faster.