Sweet another T.O. tomos rider.
For me I live and work in downtown Toronto with no indoor parking at home or work.
I've never had problems with the bike or with anyone damaging it but I do use the following lock from kryptonite.
Like I said no problems with the bike but the lock does add a sense of security. Especially when I lock it in some alley way or something.
The chain is especially great when I have nothing solid to lock the bike down to as it wraps through the front wheel and around the tank.