just bought a 3rd party battery. SDV brand at Challenger. 2100 mah, $23.90. 7.4v for my 350d. Same batt model for 400d. Vivocity outlet no more, and i bought the last piece at tiong bahru. I suggest Funan outlet if you thinking of getting . FYI, canon original that comes with the camera is 750 mah or 800mah.
The EastGear battery is also 800mah if i'm not wrong.
So does it mean your battery will last longer? Let me know how long it can last after using it.