On the subject of theft; If you were just parking your bike somewhere for a couple hours ( one time ) I would think the ( dynamo ) lamp would be fairly safe. Parking the bike outside unattended somewhere on a regular basis for longer periods I would be a little more skeptical. Doesn't matter that it's a dynamo. If someone wants it and knows the bike is parked in a regular spot it wouldn't surprise me to see someone try to pinch the lamp.

If I were to ride my bike to work I would have to remove all of the accessories that I use on my bike when I lock it up outside. That includes my front lamp, my rear lamp(s) and the frame bag for my flat repair and other items. I have some pricy stuff so no way am I going to leave it there all day. Not to mention that I have a torch mounted on one of my seat rails. If I were to remove it I would probably not be able to get it set-up again in quite the same way. That goes for the frame bag as well. This is why some people ride beaters to work. The more money and time you spend getting your bike set-up the way you want the less likely it is that you are willing to let it set somewhere ( outside ) unattended for longer periods of time.