Well everyone has thier view on how the signaling works. Being a driver I know I pay more attention to car signals then bikes with hand signals. Then again everyones comment is based in thier own enviroment. If the locals are in a bike friendly city/part-of-town then sure most will know the turn signals. Like if I was signalling downtown Toronto most cars would yield to me but if you go north of the city by 30km it's day and night as it's suburb life and thus another enviroment and they're notas friendly/understanding then downown because downtown it's congested with lots of people/bikes moving thus the drivers are slower and are more used it there then up in the 'burbs.

Perosnally I am leaning more towards the bike signalling system myself. I'd love to find one that has a front & back signalling lights controlled by one switch that makes both front/back light up/blink. I'd prefer for the back signals to be brighter then the front signals as I can see the front traffic quite a bits away but I find in my case in both enviroments up/down town back is more important as the cars are coming faster. I would still use arm signals in conjunction with the light signal just as the added visual so the driver knows I'm turning and seeing a moving arm so it's pretty much no quibble understanding that I want to turn left/right.

Zero_Enigma