We have been using Digital Ally for 5 years now. They can be downloaded by the officers at the sally port or a supervisor can use a key to swap memory sticks, so your agency can choose how they want to handle that.
I get a full week out of a memory stick and haven't had a single DUI case get lost yet. Used to happen all the time when we had Digital Patrollers.
They also have user adjustable zoom and focus and also a day/night mode depending on the lighting in your area.
My only complaint is the body mic is huge and the battery life fades dramatically with age.