Can you handhold the current 500 for a long time? I've read a lot of reviews saying that it can only be done in moderation. Since the new 500 is lighter, I assume it can be handheld for longer, and that's why I've decided that I will buy the 500 II instead of the 600 II if/when I have the money for it. If the current 500's weight allows it to be handheld most of the time, I might seriously consider the 600 II instead...