Atrix has a larger 1930 Mah battery, though i haven't used an atrix, but bigger battery should mean long lasting battery....
I have used an arc, battery life is same as that on optimus rather wrse than 2x coz in that set the light sensor can't be turned off...
Sent from my Optimus 2X using XDA App
Dont Be SmaRt WeN Yo Are NOtt
Current Dvice~Samsung GalaxY NotE 2 MetalliC
Samsung Galaxy S2 GT-I9100
Sony Ericsson Xperia Pro Mk16i
LG Optimus 2X with CM7-kangD by temasek << Second Fav fone
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>>my fav yet
Nokia 5800 XM