To test cameras out in a store, take your own memory cards and shoot some video with the cameras in the store. Then take your cards home and check them out in detail on your computer.
The main hassle I have found so far is keeping good focus when my subjects move from far to close and I am trying to focus and zoom at the same time. You can buy magnifying eyepieces for the viewscreen that make it a lot easier to keep focus. I have not done so yet. You can autofocus in video mode but it is not smooth or fast or continuous.