douglas4-
The eflite charger should work just fine for your electrifly 3S910mAh battery pack. The eflite 3S800mAh is just a little on the "light side" for operating the Axe. Do you happen to know if the eflite battery is a 10C or a 15C pack? Your estimates are probably close on the hover time. The 10.8V - 1000mAh is a NimH pack? If so, it will be substancially heavier than a comparable Li-Poly and probably won't work as well as you would probably like.