I also purchased a 3rd party. Before I even mounted it on the camera, I switched the trays from the AA to the regular battery, it immediatly got stuck, and the little tab that they have is so small and thin, i thought it was going to snap when i twisted it. After 10 min, I grabbed a thin punch and pushed the lock around. Ended up coming apart and i put it right back in the box and shipped it out for returns.
It may save you some money, but how much money are you going to lose when the battery door jams in the field and you cant change your dead batteries.